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101. Which of the following best represents Newton’s first law of motion?
ⓐ. Force equals mass times acceleration.
ⓑ. Every action has an equal and opposite reaction.
ⓒ. An object at rest will remain at rest, and an object in motion will remain in motion with constant velocity unless acted upon by a net external force.
ⓓ. Acceleration is directly proportional to the net force acting on an object and inversely proportional to its mass.
Correct Answer: An object at rest will remain at rest, and an object in motion will remain in motion with constant velocity unless acted upon by a net external force.
Explanation: Newton’s first law of motion states that objects will maintain their state of rest or uniform motion in a straight line unless acted upon by an external force.
102. Why does a book placed on a table remain at rest until someone moves it?
ⓐ. Due to the table’s friction
ⓑ. Due to the book’s weight
ⓒ. Due to the book’s inertia
ⓓ. Due to gravitational pull
Correct Answer: Due to the book’s inertia
Explanation: The book remains at rest on the table until someone moves it due to its inertia. According to Newton’s first law, objects at rest will remain at rest unless acted upon by an external force.
103. What concept explains why passengers feel thrown forward when a car suddenly accelerates?
ⓐ. Newton’s second law of motion
ⓑ. Newton’s third law of motion
ⓒ. Law of universal gravitation
ⓓ. Inertia (Newton’s first law of motion)
Correct Answer: Inertia (Newton’s first law of motion)
Explanation: Newton’s first law of motion (inertia) explains why passengers feel thrown forward when a car suddenly accelerates. Their bodies tend to remain at rest or continue moving at a constant velocity, causing them to be thrown forward relative to the car’s new motion.
104. Why does a ball rolling on a smooth surface eventually come to a stop?
ⓐ. Due to frictional forces
ⓑ. Due to gravitational pull
ⓒ. Due to air resistance
ⓓ. Due to inertia
Correct Answer: Due to frictional forces
Explanation: Rolling (and slight bearing) friction oppose motion and dissipate kinetic energy; air resistance adds a smaller contribution. Inertia would keep the ball moving only in the absence of resistive forces.
105. What happens to an astronaut inside a spaceship traveling through deep space?
ⓐ. The astronaut floats aimlessly.
ⓑ. The astronaut constantly accelerates.
ⓒ. The astronaut remains at rest.
ⓓ. The astronaut experiences weightlessness.
Correct Answer: The astronaut experiences weightlessness.
Explanation: In deep space (or in orbit), the astronaut and the craft are in free fall w\.r.t. nearby gravitating bodies, so the normal force is \~0 and the astronaut feels weightless. They may drift, but the physical effect is “apparent weightlessness.”
106. Why does a paper airplane gradually slow down and fall to the ground after being thrown?
ⓐ. Due to air resistance
ⓑ. Due to gravitational pull
ⓒ. Due to the paper’s weight
ⓓ. Due to inertia
Correct Answer: Due to air resistance
Explanation: The slowing is chiefly due to drag; the falling is due to weight $mg$. Among the options, the cause of gradual slowing down is air resistance.
107. What concept explains why an ice skater continues to glide forward even after stopping pushing?
ⓐ. Conservation of momentum
ⓑ. Law of conservation of energy
ⓒ. Newton’s second law of motion
ⓓ. Newton’s first law of motion
Correct Answer: Newton’s first law of motion
Explanation: Newton’s first law of motion explains why an ice skater continues to glide forward even after stopping pushing. The skater’s body tends to remain in motion (gliding forward) unless acted upon by an external force (such as friction or another push).
108. How does Newton’s first law of motion relate to the motion of planets in the solar system?
ⓐ. It explains why planets orbit the Sun.
ⓑ. It explains why planets move in elliptical orbits.
ⓒ. It explains why planets rotate on their axes.
ⓓ. It has no relation to planetary motion.
Correct Answer: It has no relation to planetary motion.
Explanation: First law alone predicts straight-line motion at constant $\vec v$ when $ \sum \vec F = 0$. Planetary orbits exist because the Sun’s gravity supplies centripetal acceleration ($a=v^2/r$); that’s second-law + gravitation.
109. Why is it easier to push an empty shopping cart than a fully loaded one?
ⓐ. Due to air resistance
ⓑ. Due to the cart’s shape
ⓒ. Due to the cart’s weight
ⓓ. Due to the cart’s inertia
Correct Answer: Due to the cart’s inertia
Explanation: It is easier to push an empty shopping cart than a fully loaded one due to the empty cart having less inertia. Inertia is directly proportional to mass, so the loaded cart has greater inertia, making it harder to accelerate or change its state of motion.
110. What happens to a soccer ball kicked on a frictionless surface with no gravity?
ⓐ. It moves in a straight line forever.
ⓑ. It stops immediately.
ⓒ. It moves in a circular path.
ⓓ. It moves in a random direction.
Correct Answer: It moves in a straight line forever.
Explanation: On a frictionless surface with no gravity, a soccer ball kicked will move in a straight line forever due to Newton’s first law of motion. It will continue in its initial state of motion unless acted upon by an external force.
111. What defines an inertial frame of reference in physics?
ⓐ. A frame moving with constant velocity relative to another frame
ⓑ. A frame at rest relative to a stationary object
ⓒ. A frame moving with acceleration relative to another frame
ⓓ. A frame in deep space away from any gravitational fields
Correct Answer: A frame moving with constant velocity relative to another frame
Explanation: An inertial frame of reference in physics is one that is moving with constant velocity relative to another frame, where Newton’s laws of motion can be applied without the need for additional non-inertial forces.
112. Why is it challenging to observe true inertial frames of reference on Earth?
ⓐ. Due to the presence of air resistance
ⓑ. Due to the Earth’s rotation
ⓒ. Due to gravitational forces
ⓓ. Due to magnetic fields
Correct Answer: Due to the Earth’s rotation
Explanation: Earth-fixed frames rotate (and revolve), so they are not perfectly inertial; rotation introduces fictitious forces (e.g., Coriolis).
113. How does an astronaut in a spacecraft experience inertial frames of reference?
ⓐ. By observing distant stars
ⓑ. By feeling weightlessness
ⓒ. By measuring temperature changes
ⓓ. By observing Earth’s rotation
Correct Answer: By feeling weightlessness
Explanation: An astronaut in a spacecraft experiences inertial frames of reference by feeling weightlessness. In free-fall orbit around Earth, the spacecraft and everything inside it are in a state of free-fall, creating conditions similar to those in true inertial frames.
114. Which scenario best represents an inertial frame of reference?
ⓐ. A train accelerating along a straight track
ⓑ. A car moving with constant speed along a highway
ⓒ. A boat drifting on a calm lake
ⓓ. A bicycle speeding downhill
Correct Answer: A car moving with constant speed along a highway
Explanation: A car moving with constant speed along a highway represents an inertial frame of reference because it is moving with constant velocity relative to its surroundings, allowing Newton’s laws of motion to apply without additional non-inertial forces.
115. What is the primary reason why satellites in geostationary orbit are considered to be in inertial frames of reference?
ⓐ. It is an inertial frame because its speed is constant.
ⓑ. It is an inertial frame because its altitude is constant.
ⓒ. It is not an inertial frame because it has centripetal acceleration toward Earth.
ⓓ. It is an inertial frame because it appears stationary over the equator.
Correct Answer: It is not an inertial frame because it has centripetal acceleration toward Earth.
Explanation: A body in circular orbit has $a=\dfrac{v^{2}}{r}$ toward the center. A frame attached to it is therefore non-inertial even though altitude and angular speed are constant.
116. Why does a ball thrown inside a moving train follow a curved path to an observer on the ground?
ⓐ. Due to the Coriolis effect
ⓑ. Due to gravitational forces
ⓒ. Due to air resistance
ⓓ. Due to non-inertial forces
Correct Answer: Due to gravitational forces
Explanation: The ground frame is approximately inertial; the ball has horizontal velocity from the train and vertical acceleration $g$, yielding a parabolic projectile path.
117. What characteristic distinguishes an inertial frame of reference from a non-inertial frame?
ⓐ. Uniform motion relative to distant stars
ⓑ. Zero acceleration relative to a stationary object
ⓒ. Presence of gravitational forces
ⓓ. Presence of frictional forces
Correct Answer: Zero acceleration relative to a stationary object
Explanation: Inertial frames have no acceleration (they move at constant velocity). Gravity may exist in inertial frames; its presence alone does not make a frame non-inertial.
118. How does an airplane flying at a constant speed relate to inertial frames of reference?
ⓐ. It experiences non-uniform motion.
ⓑ. It maintains a constant velocity.
ⓒ. It avoids gravitational forces.
ⓓ. It moves relative to distant galaxies.
Correct Answer: It maintains a constant velocity.
Explanation: An airplane flying at a constant speed relates to inertial frames of reference by maintaining a constant velocity relative to the ground. In this scenario, the airplane’s motion approximates an inertial frame, enabling the application of Newton’s laws.
119. Why is it challenging to maintain an inertial frame of reference on a spinning carousel?
ⓐ. Due to the carousel’s constant speed
ⓑ. Due to the carousel’s circular motion
ⓒ. Due to the carousel’s weight distribution
ⓓ. Due to the carousel’s frictional forces
Correct Answer: Due to the carousel’s circular motion
Explanation: It is challenging to maintain an inertial frame of reference on a spinning carousel due to its circular motion. Objects on the carousel experience centripetal acceleration, which introduces non-inertial forces and makes it difficult to apply Newton’s laws uniformly.
120. Which condition must be met for an elevator to represent an inertial frame of reference?
ⓐ. It must move at a constant velocity.
ⓑ. It must be stationary relative to the ground.
ⓒ. It must move with variable acceleration.
ⓓ. It must move with constant acceleration.
Correct Answer: It must move at a constant velocity.
Explanation: An elevator represents an inertial frame of reference when it moves at a constant velocity. In this state, objects inside the elevator experience uniform motion relative to the elevator, allowing Newton’s laws to apply without additional non-inertial forces.
121. Why does a passenger feel thrown forward when a bus suddenly stops?
ⓐ. Due to air resistance
ⓑ. Due to the bus’s weight
ⓒ. Due to the passenger’s inertia
ⓓ. Due to gravitational pull
Correct Answer: Due to the passenger’s inertia
Explanation: A passenger feels thrown forward when a bus suddenly stops due to their inertia. The passenger tends to remain in motion due to Newton’s first law, causing them to continue moving forward relative to the bus’s sudden deceleration.
122. How does a rocket move through space after its engines shut off?
ⓐ. Due to gravitational forces
ⓑ. Due to air resistance
ⓒ. Due to the rocket’s inertia
ⓓ. Due to the vacuum of space
Correct Answer: Due to the rocket’s inertia
Explanation: A rocket moves through space after its engines shut off due to its inertia. The rocket continues in its state of motion (velocity) unless acted upon by external forces, allowing it to coast through the vacuum of space.
123. Why does a football roll to a stop on a grass field?
ⓐ. Due to air resistance
ⓑ. Due to the football’s shape
ⓒ. Due to the football’s weight
ⓓ. Due to the grass’s friction
Correct Answer: Due to the grass’s friction
Explanation: A football rolls to a stop on a grass field primarily due to friction between the football and the grass. Although inertia initially keeps the ball moving, friction gradually slows it down until it stops.
124. What happens when a ball is thrown straight up into the air?
ⓐ. It stops immediately.
ⓑ. It continues moving upward forever.
ⓒ. It reaches a maximum height and falls back down.
ⓓ. It moves in a circular path.
Correct Answer: It reaches a maximum height and falls back down.
Explanation: When a ball is thrown straight up into the air, it reaches a maximum height due to its initial velocity overcoming gravity. Newton’s first law explains that it continues in motion until acted upon by gravity, causing it to fall back down.
125. How does a cyclist stay balanced while riding a bicycle?
ⓐ. Due to the bicycle’s weight
ⓑ. Due to air resistance
ⓒ. Due to the cyclist’s inertia
ⓓ. Due to gravitational pull
Correct Answer: Due to the cyclist’s inertia
Explanation: A cyclist stays balanced while riding a bicycle due to their inertia. The cyclist’s body tends to remain in its state of motion, helping them stay upright and balanced as they pedal forward.
126. Why does a car skid when suddenly turning on a wet road?
ⓐ. Due to the car’s weight
ⓑ. Due to air resistance
ⓒ. Due to the road’s friction
ⓓ. Due to the car’s inertia
Correct Answer: Due to the car’s inertia
Explanation: A car skids when suddenly turning on a wet road due to its inertia. The car’s tendency to continue moving forward while the tires attempt to change direction results in reduced traction and loss of control, causing a skid.
127. What allows a satellite to orbit Earth without falling?
ⓐ. Air resistance
ⓑ. Gravitational forces
ⓒ. Magnetic fields
ⓓ. Inertia
Correct Answer: Gravitational forces
Explanation: Gravity provides the required centripetal force $F_c=\dfrac{mv^2}{r}$ that bends the satellite’s inertial tendency into a closed path. Inertia supplies tangential motion, but gravity sustains the orbit.
128. Why does a feather fall more slowly than a rock in a vacuum?
ⓐ. Due to air resistance
ⓑ. Due to the feather’s shape
ⓒ. Due to gravitational pull
ⓓ. Due to the feather’s inertia
Correct Answer: Due to the feather’s inertia
Explanation: In a vacuum, a feather falls more slowly than a rock primarily due to its inertia. Both objects are affected only by gravity, but the feather’s lower mass and greater air resistance cause it to fall slower due to inertia.
129. What causes a book on a table to remain at rest until someone moves it?
ⓐ. Due to the table’s friction
ⓑ. Due to the book’s weight
ⓒ. Due to the book’s inertia
ⓓ. Due to gravitational pull
Correct Answer: Due to the book’s inertia
Explanation: A book on a table remains at rest until someone moves it due to its inertia. According to Newton’s first law, objects at rest tend to remain at rest unless acted upon by an external force, in this case, someone applying force to move the book.
130. How does a bullet fired from a gun travel in a straight line after leaving the barrel?
ⓐ. Due to air resistance
ⓑ. Due to the bullet’s shape
ⓒ. Due to the gun’s recoil
ⓓ. Due to the bullet’s inertia
Correct Answer: Due to the bullet’s inertia
Explanation: A bullet fired from a gun travels in a straight line after leaving the barrel due to its inertia. The bullet continues in its state of motion (velocity) imparted by the gun’s explosion unless acted upon by air resistance or gravity.
131. What principle describes the tendency of objects to resist changes in their state of motion?
ⓐ. Archimedes’ principle
ⓑ. Pascal’s principle
ⓒ. Newton’s first law of motion
ⓓ. Bernoulli’s principle
Correct Answer: Newton’s first law of motion
Explanation: Newton’s first law of motion describes the principle that objects tend to resist changes in their state of motion (inertia). This means objects at rest remain at rest, and objects in motion continue in a straight line at a constant velocity unless acted upon by an external force.
132. Why does a block placed on a flat surface remain stationary?
ⓐ. Due to gravitational pull
ⓑ. Due to the block’s inertia
ⓒ. Due to frictional forces
ⓓ. Due to air resistance
Correct Answer: Due to the block’s inertia
Explanation: A block placed on a flat surface remains stationary primarily due to its inertia. According to Newton’s first law, the block tends to remain at rest unless an external force, such as friction, is applied to move it.
133. How does a tightrope walker maintain balance while walking on a rope?
ⓐ. By holding a pole
ⓑ. By minimizing air resistance
ⓒ. By adjusting their center of mass
ⓓ. By increasing gravitational pull
Correct Answer: By adjusting their center of mass
Explanation: A tightrope walker maintains balance while walking on a rope by adjusting their center of mass. This adjustment counteracts the tendency of the walker’s body to deviate from equilibrium due to inertia, ensuring stability on the rope.
134. What allows a satellite in orbit around Earth to maintain a stable trajectory?
ⓐ. Gravitational forces
ⓑ. Aerodynamic drag
ⓒ. Magnetic fields
ⓓ. Inertia
Correct Answer: Gravitational forces
Explanation: Gravity supplies the centripetal force $F_c=\dfrac{mv^2}{r}$ that continually bends the satellite’s inertial tendency into an orbit.
135. Why does a ball thrown vertically into the air eventually fall back down?
ⓐ. Due to air resistance
ⓑ. Due to gravitational pull
ⓒ. Due to the ball’s inertia
ⓓ. Due to atmospheric pressure
Correct Answer: Due to gravitational pull
Explanation: A ball thrown vertically into the air eventually falls back down primarily due to gravitational pull. Newton’s first law states that objects in motion (such as the ball) will continue in motion unless acted upon by an external force (gravity), causing it to return to Earth.
136. How does a gymnast on a balance beam maintain equilibrium during a routine?
ⓐ. By reducing friction
ⓑ. By adjusting their posture
ⓒ. By increasing air resistance
ⓓ. By decreasing gravitational pull
Correct Answer: By adjusting their posture
Explanation: A gymnast on a balance beam maintains equilibrium during a routine by adjusting their posture. This adjustment helps the gymnast counteract the effects of inertia and maintain balance despite the beam’s narrow width and potential instability.
137. What causes a pendulum to swing back and forth without external force?
ⓐ. Gravitational pull
ⓑ. Aerodynamic drag
ⓒ. Magnetic fields
ⓓ. Inertia
Correct Answer: Gravitational pull
Explanation: Gravity provides the restoring torque $\tau=-mg\ell\sin\theta$ toward equilibrium; inertia carries the bob through. Without gravity there would be no oscillation.
138. Why does a spinning top remain upright and spin for a long time?
ⓐ. Due to magnetic fields
ⓑ. Due to frictional forces
ⓒ. Due to gravitational pull
ⓓ. Due to rotational inertia
Correct Answer: Due to rotational inertia
Explanation: A spinning top remains upright and spins for a long time primarily due to its rotational inertia. The top’s spinning motion maintains its stability by resisting external forces, allowing it to continue spinning upright until friction or air resistance slows it down.
139. How does a diver maintain a straight path while diving into water?
ⓐ. By minimizing air resistance
ⓑ. By adjusting their body position
ⓒ. By reducing gravitational pull
ⓓ. By increasing water resistance
Correct Answer: By adjusting their body position
Explanation: A diver maintains a straight path while diving into water by adjusting their body position. This adjustment helps the diver counteract the effects of inertia and maintain a streamlined trajectory, reducing resistance and ensuring a smooth dive.
140. Why does a car traveling on a straight road at a constant speed not require continuous acceleration?
ⓐ. Due to air resistance
ⓑ. Due to the car’s weight
ⓒ. Due to the road’s friction
ⓓ. Due to the car’s inertia
Correct Answer: Due to the car’s inertia
Explanation: A car traveling on a straight road at a constant speed does not require continuous acceleration due to its inertia. Newton’s first law states that objects in motion tend to remain in motion unless acted upon by an external force, allowing the car to maintain its speed without additional acceleration.
141. What does Newton’s second law of motion state?
ⓐ. Objects in motion tend to stay in motion
ⓑ. Force equals mass times acceleration
ⓒ. For every action, there is an equal and opposite reaction
ⓓ. In the absence of external forces, an object’s velocity remains constant
Correct Answer: Force equals mass times acceleration
Explanation: Newton’s second law of motion states that the force acting on an object is equal to the mass of the object multiplied by its acceleration. Mathematically, this is expressed as F = ma, where F is force, m is mass, and a is acceleration.
142. If the force acting on an object is doubled, how does its acceleration change, assuming the mass remains constant?
ⓐ. It doubles
ⓑ. It halves
ⓒ. It quadruples
ⓓ. It remains the same
Correct Answer: It doubles
Explanation: According to Newton’s second law (F = ma), if the force acting on an object is doubled and the mass remains constant, its acceleration will also double. This is because acceleration is directly proportional to the force applied, given a constant mass.
143. How does the mass of an object affect its acceleration, given a constant force?
ⓐ. More mass results in higher acceleration
ⓑ. Less mass results in higher acceleration
ⓒ. Mass has no effect on acceleration
ⓓ. More mass results in lower acceleration
Correct Answer: More mass results in lower acceleration
Explanation: According to Newton’s second law (F = ma), given a constant force, the acceleration of an object decreases as its mass increases. More mass requires more force to achieve the same acceleration, while less mass requires less force for the same acceleration.
144. What happens to the acceleration of an object if the applied force is reduced to zero?
ⓐ. It increases indefinitely
ⓑ. It remains constant
ⓒ. It decreases to zero
ⓓ. It fluctuates unpredictably
Correct Answer: It decreases to zero
Explanation: If the applied force on an object is reduced to zero, according to Newton’s second law (F = ma), the acceleration of the object will decrease and eventually become zero. This means the object will either come to rest or continue at a constant velocity if no other forces act upon it.
145. How does Newton’s second law relate to the concept of inertia?
ⓐ. It explains the origin of inertia
ⓑ. It quantifies the resistance to motion
ⓒ. It describes the behavior of friction
ⓓ. It defines the units of inertia
Correct Answer: It quantifies the resistance to motion
Explanation: Newton’s second law (F = ma) quantifies the resistance to changes in motion (inertia) by relating the force applied to an object’s mass and resulting acceleration. Inertia refers to an object’s tendency to resist changes in its state of motion, as described by Newton’s laws.
146. Which physical quantity does Newton’s second law help calculate?
ⓐ. Weight
ⓑ. Volume
ⓒ. Density
ⓓ. Acceleration
Correct Answer: Acceleration
Explanation: Newton’s second law (F = ma) helps calculate acceleration, where F is force, m is mass, and a is acceleration. This formula is crucial for determining how objects respond to forces and how their motion changes under the influence of external forces.
147. Why does a heavier object require more force to accelerate at the same rate as a lighter object?
ⓐ. Due to gravitational pull
ⓑ. Due to air resistance
ⓒ. Due to the object’s mass
ⓓ. Due to the object’s weight
Correct Answer: Due to the object’s mass
Explanation: A heavier object requires more force to accelerate at the same rate as a lighter object due to its greater mass. According to Newton’s second law (F = ma), more mass requires more force to achieve the same acceleration, reflecting the object’s resistance to changes in motion.
148. How does Newton’s second law explain the motion of a car accelerating from rest?
ⓐ. It determines the car’s top speed
ⓑ. It predicts the car’s braking distance
ⓒ. It relates the force applied to the car’s mass and acceleration
ⓓ. It quantifies the car’s fuel consumption
Correct Answer: It relates the force applied to the car’s mass and acceleration
Explanation: Newton’s second law (F = ma) explains the motion of a car accelerating from rest by relating the force applied to the car’s mass and resulting acceleration. This law helps quantify the force needed to accelerate the car and understand its motion dynamics.
149. What principle does Newton’s second law extend from Newton’s first law?
ⓐ. Principle of equilibrium
ⓑ. Law of inertia
ⓒ. Law of action and reaction
ⓓ. Law of universal gravitation
Correct Answer: Law of inertia
Explanation: Newton’s second law extends from Newton’s first law (law of inertia) by quantifying the relationship between force, mass, and acceleration. It builds upon the idea that objects resist changes in their state of motion unless acted upon by an external force, providing a mathematical basis for understanding motion.
150. How does Newton’s second law apply to the motion of a rocket in space?
ⓐ. It determines the rocket’s launch trajectory
ⓑ. It relates the rocket’s thrust to its acceleration
ⓒ. It predicts the rocket’s orbit around Earth
ⓓ. It quantifies the rocket’s fuel efficiency
Correct Answer: It relates the rocket’s thrust to its acceleration
Explanation: Newton’s second law (F = ma) applies to the motion of a rocket in space by relating the thrust generated by its engines (force) to the rocket’s mass and resulting acceleration. This relationship is crucial for calculating how much force is needed to accelerate the rocket and propel it through space.
151. In the equation F = ma, what does ‘F’ represent?
ⓐ. Acceleration
ⓑ. Mass
ⓒ. Force
ⓓ. Velocity
Correct Answer: Force
Explanation: In the equation F = ma, ‘F’ represents force. This formula, derived from Newton’s second law of motion, states that the force acting on an object is equal to its mass multiplied by its acceleration.
152. If an object of mass 5 kg experiences an acceleration of 2 m/s², what is the magnitude of the force acting on it?
ⓐ. 2 N
ⓑ. 5 N
ⓒ. 10 N
ⓓ. 15 N
Correct Answer: 10 N
Explanation: According to F = ma, where m = 5 kg and a = 2 m/s², the force ‘F’ acting on the object can be calculated as F = 5 kg × 2 m/s² = 10 N. Therefore, the magnitude of the force is 10 Newtons.
153. How does doubling the mass of an object affect the force required to achieve the same acceleration?
ⓐ. The force halves
ⓑ. The force doubles
ⓒ. The force quadruples
ⓓ. The force remains the same
Correct Answer: The force doubles
Explanation: According to F = ma, if the mass (m) of an object is doubled and the acceleration (a) remains constant, the force (F) required will double. This is because force is directly proportional to mass for a given acceleration.
154. If a force of 20 N is applied to an object with an acceleration of 4 m/s², what is the mass of the object?
ⓐ. 2 kg
ⓑ. 4 kg
ⓒ. 5 kg
ⓓ. 8 kg
Correct Answer: 5 kg
Explanation: Using F = ma, where F = 20 N and a = 4 m/s², we can calculate the mass (m) of the object as m = F / a = 20 N / 4 m/s² = 5 kg. Therefore, the mass of the object is 5 kilograms.
155. Which physical quantity is represented by ‘a’ in the equation F = ma?
ⓐ. Acceleration
ⓑ. Force
ⓒ. Mass
ⓓ. Velocity
Correct Answer: Acceleration
Explanation: In the equation F = ma, ‘a’ represents acceleration. Acceleration is the rate of change of velocity with respect to time and is a crucial parameter in Newton’s second law of motion.
156. How does Newton’s second law relate force to acceleration?
ⓐ. Force is inversely proportional to acceleration
ⓑ. Force is directly proportional to acceleration
ⓒ. Force is independent of acceleration
ⓓ. Force is proportional to mass only
Correct Answer: Force is directly proportional to acceleration
Explanation: Newton’s second law (F = ma) states that force is directly proportional to acceleration when mass is constant. This means that doubling the force will double the acceleration, provided the mass remains the same.
157. What happens to the acceleration of an object if the force acting on it is increased while its mass remains constant?
ⓐ. Acceleration decreases
ⓑ. Acceleration increases
ⓒ. Acceleration remains constant
ⓓ. Acceleration becomes zero
Correct Answer: Acceleration increases
Explanation: According to F = ma, if the force acting on an object increases and its mass remains constant, the acceleration of the object will increase. This is because acceleration is directly proportional to force, given a constant mass.
158. Which aspect of motion does the equation F = ma quantify?
ⓐ. Speed
ⓑ. Direction
ⓒ. Acceleration
ⓓ. Position
Correct Answer: Acceleration
Explanation: The equation F = ma quantifies acceleration, which is the rate of change of an object’s velocity with respect to time. It relates the force applied to an object to the resulting acceleration, providing a measure of how quickly the object’s velocity changes under the influence of the force.
159. How does Newton’s second law allow scientists to predict the motion of objects?
ⓐ. By calculating their initial velocity
ⓑ. By determining their final position
ⓒ. By analyzing their weight
ⓓ. By applying force and mass relations
Correct Answer: By applying force and mass relations
Explanation: Newton’s second law (F = ma) allows scientists to predict the motion of objects by applying the relationship between force, mass, and acceleration. This law provides a fundamental basis for understanding and calculating how objects move under the influence of applied forces.
160. Why is the equation F = ma considered a fundamental principle in physics?
ⓐ. It defines the concept of time
ⓑ. It quantifies the concept of force
ⓒ. It describes the behavior of light
ⓓ. It relates force to changes in motion
Correct Answer: It relates force to changes in motion
Explanation: The equation F = ma is considered fundamental in physics because it relates force to changes in an object’s motion. It provides a quantitative measure of how forces cause accelerations in objects, offering insights into the dynamics of motion and interaction between objects.
161. What is the SI unit of force?
ⓐ. Newton
ⓑ. Joule
ⓒ. Watt
ⓓ. Pascal
Correct Answer: Newton
Explanation: The SI unit of force is the Newton (N). It is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared.
162. Which unit is commonly used to measure small forces, such as those in microscopic or atomic scales?
ⓐ. Newton
ⓑ. Dyne
ⓒ. Kilogram-force
ⓓ. Pound-force
Correct Answer: Dyne
Explanation: The dyne (dyn) is commonly used to measure small forces, particularly in microscopic or atomic scales. It is defined as the force required to accelerate a mass of one gram at a rate of one centimeter per second squared.
163. What is the relationship between Newton and dyne?
ⓐ. 1 N = 10 dyn
ⓑ. 1 N = 100 dyn
ⓒ. 1 N = 1000 dyn
ⓓ. 1 N = 100000 dyn
Correct Answer: 1 N = 100000 dyn
Explanation: In CGS, $1~\mathrm{dyn} = 1~\mathrm{g\cdot cm\,s^{-2}}$. Converting $1~\mathrm{N} = 1~\mathrm{kg\cdot m\,s^{-2}} = 1000~\mathrm{g}\times 100~\mathrm{cm\,s^{-2}} = 10^5~\mathrm{dyn}$.
164. Which unit of force is based on the gravitational force acting on a mass of one kilogram?
ⓐ. Newton
ⓑ. Dyne
ⓒ. Kilogram-force
ⓓ. Pound-force
Correct Answer: Kilogram-force
Explanation: The kilogram-force (kgf) is a unit of force based on the gravitational force acting on a mass of one kilogram under standard gravity (9.80665 m/s²). It is commonly used in some engineering contexts.
165. What is the approximate value of standard gravity used in the definition of kilogram-force?
ⓐ. 9.81 m/s²
ⓑ. 10 m/s²
ⓒ. 9.8 m/s²
ⓓ. 9.83 m/s²
Correct Answer: 9.81 m/s²
Explanation: The standard gravity used in the definition of kilogram-force is approximately 9.81 m/s². This value represents the average acceleration due to gravity at the Earth’s surface.
166. Which unit of force is defined as the force required to accelerate a mass of one pound at a rate of one foot per second squared?
ⓐ. Newton
ⓑ. Dyne
ⓒ. Kilogram-force
ⓓ. Poundal
Correct Answer: Poundal
Explanation: By definition, $1~\mathrm{poundal}$ (pdl) is the force that accelerates $1~\mathrm{lbm}$ at $1~\mathrm{ft\,s^{-2}}$. Pound-force (lbf) instead equals the weight of $1~\mathrm{lbm}$ under standard gravity, $1~\mathrm{lbf} \approx 32.174~\mathrm{pdl}$.
167. What is the relationship between Newton and pound-force?
ⓐ. 1 N = 0.2248 lbf
ⓑ. 1 N = 2.2046 lbf
ⓒ. 1 N = 0.4536 lbf
ⓓ. 1 N = 4.4482 lbf
Correct Answer: 1 N = 0.2248 lbf
Explanation: Since $1\ \text{lbf} \approx 4.44822\ \text{N}$, the inverse is $1\ \text{N} \approx 0.22481\ \text{lbf}$.
168. Which unit of mass is commonly used alongside the Newton in calculations of force?
ⓐ. Kilogram
ⓑ. Gram
ⓒ. Pound
ⓓ. Ounce
Correct Answer: Kilogram
Explanation: The kilogram (kg) is commonly used alongside the Newton (N) in calculations of force, where force (F) is expressed as F = ma. Here, ‘m’ represents mass in kilograms.
169. Which unit of mass is equivalent to 1000 grams?
ⓐ. Kilogram
ⓑ. Gram
ⓒ. Pound
ⓓ. Ounce
Correct Answer: Kilogram
Explanation: The kilogram (kg) is equivalent to 1000 grams. It is the base unit of mass in the International System of Units (SI).
170. Which unit of mass is commonly used in the context of atomic and molecular scales?
ⓐ. Kilogram
ⓑ. Gram
ⓒ. Atomic mass unit
ⓓ. Ounce
Correct Answer: Atomic mass unit
Explanation: The atomic mass unit (amu) is commonly used in the context of atomic and molecular scales to express the masses of atoms and molecules relative to the mass of a carbon-12 atom.
171. What force is required to accelerate a 1000 kg car at 2 m/s²?
ⓐ. 500 N
ⓑ. 1000 N
ⓒ. 2000 N
ⓓ. 5000 N
Correct Answer: 2000 N
Explanation: According to F = ma, where m = 1000 kg and a = 2 m/s², the force ‘F’ required to accelerate the car can be calculated as F = 1000 kg × 2 m/s² = 2000 N. Therefore, the force required is 2000 Newtons.
172. A 50 kg person jumps with an acceleration of 5 m/s². What force does the ground exert on the person during the jump?
ⓐ. 100 N
ⓑ. 150 N
ⓒ. 200 N
ⓓ. 250 N
Correct Answer: 250 N
Explanation: According to F = ma, where m = 50 kg and a = 5 m/s², the force exerted by the ground (which is the reaction force to the person’s jump) can be calculated as F = 50 kg × 5 m/s² = 250 N. Therefore, the ground exerts a force of 250 Newtons on the person.
173. According to Newton’s third law of motion, for every action, there is an equal and opposite ___________.
ⓐ. Reaction
ⓑ. Acceleration
ⓒ. Force
ⓓ. Mass
Correct Answer: Reaction
Explanation: Newton’s third law states that for every action, there is an equal and opposite reaction. This means that whenever one object exerts a force on a second object, the second object exerts a force of equal magnitude in the opposite direction on the first object.
174. If object A exerts a force of 10 N on object B, according to Newton’s third law, what force does object B exert on object A?
ⓐ. 10 N
ⓑ. 20 N
ⓒ. 5 N
ⓓ. 0 N
Correct Answer: 10 N
Explanation: According to Newton’s third law, the force exerted by object B on object A is equal in magnitude and opposite in direction to the force exerted by object A on object B. Therefore, object B exerts a force of 10 N on object A.
175. When a person pushes against a wall with a force, according to Newton’s third law, the wall exerts an equal and opposite force ____________.
ⓐ. Perpendicular to the person
ⓑ. Parallel to the person
ⓒ. At an angle to the person
ⓓ. Against the person
Correct Answer: Against the person
Explanation: According to Newton’s third law, when a person pushes against a wall with a force, the wall exerts an equal and opposite force against the person. This force acts in the direction opposite to the person’s push, preventing them from moving through the wall.
176. Which of the following scenarios best exemplifies Newton’s third law of motion?
ⓐ. A car accelerates forward on a straight road.
ⓑ. A rocket launches into space.
ⓒ. A ball bounces off a wall.
ⓓ. A boat sails on a calm lake.
Correct Answer: A ball bounces off a wall.
Explanation: When a ball bounces off a wall, it experiences a force from the wall (the reaction force) that is equal in magnitude and opposite in direction to the force with which the ball initially struck the wall. This scenario illustrates Newton’s third law of motion.
177. In Newton’s third law, what is meant by “equal and opposite” forces?
ⓐ. The forces have equal magnitudes but opposite directions.
ⓑ. The forces are equal in duration but opposite in application.
ⓒ. The forces are equal in size but opposite in type.
ⓓ. The forces are equal in speed but opposite in motion.
Correct Answer: The forces have equal magnitudes but opposite directions.
Explanation: According to Newton’s third law, “equal and opposite” forces refer to forces that have equal magnitudes (strengths) but act in opposite directions. This principle applies to all interactions between objects.
178. When a rocket accelerates upwards, according to Newton’s third law, the rocket pushes against the exhaust gases and the exhaust gases push \_\_\_\_\_\_\_\_.
ⓐ. The rocket downwards
ⓑ. The rocket forwards
ⓒ. The rocket upwards
ⓓ. No force on the rocket
Correct Answer: The rocket upwards
Explanation: The engine expels mass backward; the equal and opposite force from the exhaust acts upwards on the rocket (thrust).
179. Why is Newton’s third law important in understanding motion and forces?
ⓐ. It defines the relationship between velocity and acceleration.
ⓑ. It explains how objects resist changes in their motion.
ⓒ. It quantifies the gravitational attraction between objects.
ⓓ. It ensures conservation of momentum in collisions.
Correct Answer: It ensures conservation of momentum in collisions.
Explanation: Internal forces occur in equal-and-opposite pairs; for isolated systems $\sum \Delta \vec p=0$, so total momentum is conserved.
180. When a swimmer pushes against the water with their hands, according to Newton’s third law, the water exerts an equal and opposite force ________.
ⓐ. On the swimmer’s feet
ⓑ. On the swimmer’s hands
ⓒ. On the swimmer’s body
ⓓ. On the swimmer’s arms
Correct Answer: On the swimmer’s body
Explanation: According to Newton’s third law, when a swimmer pushes against the water with their hands, the water exerts an equal and opposite force on the swimmer’s body. This force acts in the direction opposite to the swimmer’s push and helps propel the swimmer through the water.
Sure, here are more quizzes focusing on the sub-topic “Action and Reaction Forces”:
181. In Newton’s third law of motion, action and reaction forces always act on __________.
ⓐ. Different objects
ⓑ. The same object
ⓒ. Objects of different masses
ⓓ. Objects moving in opposite directions
Correct Answer: Different objects
Explanation: According to Newton’s third law, action and reaction forces always act on different objects. When one object exerts a force on a second object, the second object simultaneously exerts a force of equal magnitude in the opposite direction on the first object.
182. When you push a heavy box across the floor, according to Newton’s third law, the box exerts a reaction force __________.
ⓐ. Against your push
ⓑ. In the direction of your push
ⓒ. Perpendicular to your push
ⓓ. At an angle to your push
Correct Answer: Against your push
Explanation: According to Newton’s third law, when you push a heavy box across the floor, the box exerts a reaction force against your push. This reaction force acts in the direction opposite to your push and prevents you from simply passing through the box.
183. A car accelerates forward due to the action of its engine. According to Newton’s third law, what is the reaction force to this forward motion?
ⓐ. Friction from the road
ⓑ. Wind resistance
ⓒ. Air resistance
ⓓ. Force of gravity
Correct Answer: Friction from the road
Explanation: According to Newton’s third law, when a car accelerates forward due to the action of its engine, the reaction force to this forward motion is the frictional force exerted by the road on the car’s tires. This frictional force acts in the direction opposite to the car’s forward motion.
184. When a cannon fires a cannonball, according to Newton’s third law, what is the reaction force to the force exerted on the cannonball?
ⓐ. Recoil force on the cannon
ⓑ. Air resistance on the cannonball
ⓒ. Gravitational force on the cannonball
ⓓ. Magnetic force on the cannonball
Correct Answer: Recoil force on the cannon
Explanation: According to Newton’s third law, when a cannon fires a cannonball, the reaction force to the force exerted on the cannonball (forward) is the recoil force exerted on the cannon (backward). This recoil force causes the cannon to move in the opposite direction to the fired cannonball.
185. When a person jumps off a boat onto a dock, according to Newton’s third law, what is the reaction force to the person’s jump?
ⓐ. The force exerted by the dock on the person
ⓑ. The force exerted by the person on the dock
ⓒ. The gravitational force on the person
ⓓ. The force exerted by the boat on the person
Correct Answer: The force exerted by the person on the dock
Explanation: According to Newton’s third law, when a person jumps off a boat onto a dock, the reaction force to the person’s jump is the force exerted by the person on the dock. This force acts in the direction opposite to the person’s jump.
186. When a rocket engine ejects exhaust gases downwards, according to Newton’s third law, what is the reaction force to the downward ejection?
ⓐ. Thrust force upwards on the rocket
ⓑ. Gravitational force downwards on the rocket
ⓒ. Air resistance force on the rocket
ⓓ. Frictional force on the rocket
Correct Answer: Thrust force upwards on the rocket
Explanation: According to Newton’s third law, when a rocket engine ejects exhaust gases downwards, the reaction force to the downward ejection is the thrust force exerted upwards on the rocket. This thrust force propels the rocket upwards into space.
187. Which of the following scenarios does not exemplify Newton’s third law of motion?
ⓐ. A swimmer pushes against the water, and the water pushes the swimmer forward.
ⓑ. A tennis player hits a ball with a racket, and the ball accelerates away from the racket.
ⓒ. A horse pulls a cart, and the cart pulls the horse forward.
ⓓ. A bird flies in the air and experiences lift due to its wings’ interaction with the air.
Correct Answer: A bird flies in the air and experiences lift due to its wings’ interaction with the air.
Explanation: Option D describes aerodynamics and lift generation, which involve fluid dynamics principles and Bernoulli’s principle, rather than Newton’s third law of motion.
188. When a person walks on the ground, according to Newton’s third law, what is the reaction force to the person’s foot pushing against the ground?
ⓐ. Frictional force between the foot and the ground
ⓑ. Gravitational force acting on the person
ⓒ. Normal force exerted by the ground on the person’s foot
ⓓ. Air resistance opposing the person’s motion
Correct Answer: Normal force exerted by the ground on the person’s foot
Explanation: According to Newton’s third law, when a person walks on the ground, the reaction force to the person’s foot pushing against the ground is the normal force exerted by the ground on the person’s foot. This normal force acts perpendicular to the surface of contact and supports the person’s weight.
189. Which law of motion states that forces always occur in pairs and act on different objects simultaneously?
ⓐ. Newton’s First Law
ⓑ. Newton’s Second Law
ⓒ. Newton’s Third Law
ⓓ. Law of Inertia
Correct Answer: Newton’s Third Law
Explanation: Newton’s third law states that forces always occur in pairs and act on different objects simultaneously. This law explains the interaction between objects and is fundamental in understanding action and reaction forces.
190. When a soccer player kicks a ball, according to Newton’s third law, what is the reaction force to the player’s kick?
ⓐ. Air resistance on the ball
ⓑ. Gravitational force on the ball
ⓒ. Force of friction on the player’s foot
ⓓ. Force of the ball on the player’s foot
Correct Answer: Force of the ball on the player’s foot
Explanation: According to Newton’s third law, when a soccer player kicks a ball, the reaction force to the player’s kick is the force exerted by the ball on the player’s foot. This force acts in the direction opposite to the player’s kick.
191. When a person jumps off a diving board, according to Newton’s third law, what is the reaction force to the person’s push against the board?
ⓐ. The force exerted by the diving board on the person
ⓑ. The force exerted by the person on the diving board
ⓒ. The gravitational force on the person
ⓓ. The frictional force on the person’s feet
Correct Answer: The force exerted by the diving board on the person
Explanation: According to Newton’s third law, when a person jumps off a diving board, the reaction force to the person’s push against the board is the force exerted by the diving board on the person. This reaction force propels the person upwards into the air.
192. When a car collides with a wall, according to Newton’s third law, what is the reaction force to the car’s impact?
ⓐ. The force exerted by the wall on the car
ⓑ. The force exerted by the car on the wall
ⓒ. The frictional force between the car and the road
ⓓ. The gravitational force on the car
Correct Answer: The force exerted by the wall on the car
Explanation: According to Newton’s third law, when a car collides with a wall, the reaction force to the car’s impact is the force exerted by the wall on the car. This reaction force acts in the direction opposite to the car’s motion and causes the car to come to a stop.
193. In a rocket launch, according to Newton’s third law, what is the reaction force to the expulsion of exhaust gases?
ⓐ. Thrust force upwards on the rocket
ⓑ. Air resistance force on the rocket
ⓒ. Gravitational force on the rocket
ⓓ. Frictional force on the rocket
Correct Answer: Thrust force upwards on the rocket
Explanation: According to Newton’s third law, in a rocket launch, the reaction force to the expulsion of exhaust gases downwards is the thrust force exerted upwards on the rocket. This thrust force propels the rocket upwards into space.
194. When a swimmer pushes against the water with their hands, according to Newton’s third law, what is the reaction force?
ⓐ. The force exerted by the swimmer on the water
ⓑ. The force exerted by the water on the swimmer
ⓒ. The force of gravity on the swimmer
ⓓ. The force exerted by the swimmer’s body on the water
Correct Answer: The force exerted by the water on the swimmer
Explanation: According to Newton’s third law, when a swimmer pushes against the water with their hands, the reaction force to the swimmer’s push is the force exerted by the water on the swimmer. This reaction force propels the swimmer forward through the water.
195. When a person walks on the ground, according to Newton’s third law, what is the reaction force to the person’s foot pushing against the ground?
ⓐ. Frictional force between the foot and the ground
ⓑ. Gravitational force acting on the person
ⓒ. Normal force exerted by the ground on the person’s foot
ⓓ. Air resistance opposing the person’s motion
Correct Answer: Normal force exerted by the ground on the person’s foot
Explanation: According to Newton’s third law, when a person walks on the ground, the reaction force to the person’s foot pushing against the ground is the normal force exerted by the ground on the person’s foot. This normal force supports the person’s weight and allows them to walk.
196. When a hockey player hits a puck with a stick, according to Newton’s third law, what is the reaction force to the player’s hit?
ⓐ. The force exerted by the puck on the stick
ⓑ. The force exerted by the stick on the puck
ⓒ. The frictional force between the puck and the ice
ⓓ. The gravitational force on the puck
Correct Answer: The force exerted by the puck on the stick
Explanation: According to Newton’s third law, when a hockey player hits a puck with a stick, the reaction force to the player’s hit is the force exerted by the puck on the stick. This reaction force causes the puck to accelerate in the direction opposite to the player’s hit.
197. In a rocket launch, when the rocket engine ignites, according to Newton’s third law, what is the reaction force?
ⓐ. Gravitational force on the rocket
ⓑ. Air resistance force on the rocket
ⓒ. Thrust force exerted upwards on the rocket
ⓓ. Frictional force on the rocket
Correct Answer: Thrust force exerted upwards on the rocket
Explanation: According to Newton’s third law, in a rocket launch, when the rocket engine ignites and ejects exhaust gases downwards, the reaction force to this downward ejection is the thrust force exerted upwards on the rocket. This thrust force propels the rocket upwards into space.
198. When a person pushes a heavy box along the floor, according to Newton’s third law, what is the reaction force to the person’s push?
ⓐ. The force exerted by the person on the box
ⓑ. The frictional force between the box and the floor
ⓒ. The gravitational force on the box
ⓓ. The force exerted by the box on the person
Correct Answer: The force exerted by the box on the person
Explanation: According to Newton’s third law, when a person pushes a heavy box along the floor, the reaction force to the person’s push is the force exerted by the box on the person. This reaction force acts in the direction opposite to the person’s push.
199. When a bird flies by flapping its wings, according to Newton’s third law, what is the reaction force to the bird’s wing movement?
ⓐ. Lift force generated by the wings
ⓑ. Gravitational force acting on the bird
ⓒ. Air resistance force opposing the bird’s motion
ⓓ. Force exerted by the bird’s body on the air
Correct Answer: Force exerted by the bird’s body on the air
Explanation: According to Newton’s third law, when a bird flies by flapping its wings, the reaction force to the bird’s wing movement is the force exerted by the bird’s body on the surrounding air. This reaction force propels the bird forward through the air.
200. When a car accelerates forward on a road, according to Newton’s third law, what is the reaction force to the car’s acceleration?
ⓐ. Air resistance force on the car
ⓑ. Gravitational force on the car
ⓒ. Frictional force between the tires and the road
ⓓ. Force exerted by the road on the car
Correct Answer: Force exerted by the road on the car
Explanation: According to Newton’s third law, when a car accelerates forward on a road, the reaction force to the car’s acceleration is the force exerted by the road on the car. This reaction force provides the forward propulsion necessary for the car’s acceleration.
You are now on Class 11 Physics MCQs – Chapter 5: Laws of Motion (Part 2). This chapter plays a vital role in understanding the NCERT/CBSE Class 11 Physics syllabus and prepares students for both board exams and competitive exams like JEE, NEET, and state-level entrance tests. Across all 5 parts, there are a total of 490 MCQs with detailed answers, designed to test conceptual understanding and application skills. In this part, you will practice another 100 MCQs with explanations, focusing on friction, dynamics of motion, and advanced applications of Newton’s Laws.
- 👉 This is Part 2 — 100 solved MCQs for in-depth practice.
- 👉 Best suited for competitive exams like JEE/NEET and board exam revision.
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- 👉 Proceed to Part 3 for the next 100 questions.