Laws of Motion — NEET Physics MCQs with answers

Laws of Motion is a Class 11 Physics chapter in the NEET (UG) syllabus. NEET720 has 999 reviewed practice questions on it, each with a quick answer and a step-by-step explanation. The 8 questions below are free and fixed, so you can bookmark this page; the full chapter, plus mistake tracking and spaced revision, is in the app.

Topics covered

Atwood Machine · Apparent Weight · Circular Motion Dynamics · Momentum and Impulse · Newton's First Law · Equilibrium of Forces · Pseudo Force · Newton's Laws of Motion · Connected Bodies and Pulleys · Accelerating Frames and Apparent Weight · Pseudo force in non-inertial frames · Newton's laws and momentum · Connected bodies — pulleys · Equilibrium and free-body diagrams · Connected bodies, pulleys and lifts · Friction · Dynamics of uniform circular motion · Impulse and momentum change · Momentum and its conservation · Impulse and momentum conservation · Pulleys and connected bodies · Blocks on inclines · Motion in a vertical circle · Circular motion — banking of roads · Recoil and variable mass systems · Impulse-momentum theorem · Pulleys and springs · Normal force · Circular motion — vertical circle · Newton's laws — non-inertial frames · Newton's laws and free-body diagrams · Circular motion on a rotating platform · Pulleys — limiting case · Motion on an inclined plane · Variable mass systems · Spring forces · Pseudo forces · Impulse and momentum · Conservation of momentum · Circular dynamics

8 free Laws of Motion practice questions with answers

Choose an answer in your head before opening it. Each explanation says why the correct option is right and, where relevant, why the tempting wrong option is wrong.

1. Question 1 · medium · Dynamics of uniform circular motion

   A car takes a sharp left turn and a passenger slides toward the right-hand door. Viewed from the ground (an inertial frame), the correct explanation is:

   • A.a real centrifugal force pushes the passenger outward, away from the centre of the turn
   • B.the passenger tends to continue in a straight line while the car curves beneath them
   • C.the reaction pair of the centripetal force acts on the passenger and pushes them outward
   • D.friction from the seat pushes the passenger outward
   Show answer and explanation

   Answer: B. the passenger tends to continue in a straight line while the car curves beneath them

   By Newton's first law the passenger's body tends to keep its straight-line motion. The car turns left underneath, so relative to the car the passenger drifts right. No real outward force acts in the ground frame.

   In the ground frame, turning left requires an inward (leftward) centripetal force. Until friction from the seat builds up (or the door supplies a normal force), the passenger's body continues along its original straight-line path — pure inertia. Relative to the turning car this appears as an outward slide, but no outward force exists in the inertial frame. Option A invokes the centrifugal pseudo-force, which is a bookkeeping device valid only in the car's rotating (non-inertial) frame. Option C misuses Newton's third law: the reaction to a force on the passenger never acts on the passenger. Option D reverses the actual direction of seat friction.

   Common mistake: Treating centrifugal force as a real force in the ground frame

2. Question 2 · medium · Dynamics of uniform circular motion

   For a car turning on a level road, the centripetal force needed to keep it on the circular path is provided by:

   • A.a distinct new force, in addition to gravity, the normal reaction and friction
   • B.the car's own engine power, converted directly into centripetal force
   • C.friction between the tyres and the road, which is the net real inward force here
   • D.the normal reaction alone, since the road is level
   Show answer and explanation

   Answer: C. friction between the tyres and the road, which is the net real inward force here

   'Centripetal force' is not a new kind of force — it is simply the name for whatever net real force points toward the centre. On a level road, only friction has a horizontal component, so friction alone supplies it.

   Centripetal force is a descriptive, not a fundamental, category of force: it refers to the net component of the actual forces (gravity, normal reaction, tension, friction, etc.) directed toward the centre of the circular path. On a flat, unbanked road, gravity and the normal reaction are both purely vertical and cancel; the only force with a horizontal component is friction between tyres and road, so friction alone must supply the entire centripetal force. Drawing a separate 'centripetal force' arrow on a free-body diagram in addition to the real forces double-counts a force that doesn't independently exist.

   Common mistake: Drawing centripetal force as an extra arrow alongside the real forces in a free-body diagram

3. Question 3 · medium · Connected bodies, pulleys and lifts

   In an Atwood machine, the magnitude of tension is assumed to be the same at every point of the string and on both sides of the pulley. This assumption is justified only if:

   • A.the string is inextensible, whatever the masses of the string and pulley
   • B.the string is massless and the pulley is massless and frictionless
   • C.the two suspended masses are equal
   • D.the pulley is rigid and firmly clamped to its support
   Show answer and explanation

   Answer: B. the string is massless and the pulley is massless and frictionless

   A massless string needs zero net force on each element, so tension cannot vary along it; a massless, frictionless pulley needs zero net torque, so tension is equal on both sides.

   Consider an element of string of mass dm: the tension difference across it is dT = (dm)a. If the string is massless, dm = 0, so T is uniform along each straight section. Across the pulley, unequal tensions would exert a net torque; a pulley with zero moment of inertia and zero axle/surface friction requires zero net torque, forcing T₁ = T₂. Inextensibility (option A) serves a different purpose — it makes both blocks share one acceleration magnitude. Equal masses (option C) are irrelevant to the tension-uniformity assumption. When later chapters give the pulley mass, the two tensions genuinely differ.

   Common mistake: Crediting inextensibility, rather than masslessness, for uniform tension

4. Question 4 · medium · Friction

   A rear-wheel-drive car accelerates forward from rest on a level road without its wheels slipping. The friction force exerted by the road on the rear (driving) wheels:

   • A.acts backward, because friction always opposes motion
   • B.is zero, because the wheels roll without slipping
   • C.acts backward on the driving wheels and forward on the front wheels
   • D.acts forward, in the direction of the car's acceleration
   Show answer and explanation

   Answer: D. acts forward, in the direction of the car's acceleration

   The engine spins the rear wheels so their contact points tend to slip backward relative to the road; static friction opposes this tendency and therefore pushes the car forward. It is the external force that accelerates the car.

   Friction opposes relative sliding (or its tendency) between the surfaces in contact — not the body's overall motion. The engine's torque makes the driven wheel's contact point tend to skid backward against the road, so the road exerts forward static friction on it. This forward friction is the only external horizontal force available to accelerate the car; internal engine forces cannot accelerate the centre of mass. Option A applies the slogan 'friction opposes motion' incorrectly. Option B confuses 'no slipping' with 'no friction' — static friction exists without sliding. Option C reverses the actual situation.

   Common mistake: Assuming friction must always point opposite to the vehicle's velocity

5. Question 5 · easy · Newton's laws and momentum

   A city bus starts moving forward suddenly from rest. Standing passengers who are not holding the handrail tend to fall backward. The best explanation is:

   • A.The bus floor exerts a backward reaction force on the passengers as it accelerates
   • B.The air inside the bus rushes backward and pushes the passengers with it
   • C.The feet are carried forward with the bus while the upper body tends to remain at rest due to inertia
   • D.Friction between the shoes and the floor disappears the moment the bus accelerates
   Show answer and explanation

   Answer: C. The feet are carried forward with the bus while the upper body tends to remain at rest due to inertia

   Friction carries the feet forward with the accelerating bus, but no comparable force acts on the upper body, which by inertia of rest tends to stay where it was. Relative to the bus, the passenger appears to fall backward.

   Principle: Newton's first law (inertia of rest). When the bus accelerates, friction from the floor acts on the passenger's feet and accelerates them forward with the bus. The upper body receives no such immediate forward force, so it tends to continue in its state of rest. Relative to the accelerating bus, the upper body therefore lags, and the passenger tilts backward. Option A is wrong because the floor's friction on the feet is forward, not backward. Option B is wrong because internal air motion is negligible. Option D is wrong because friction is present and is the very force coupling the feet to the bus.

   Common mistake: Inventing a backward 'reaction force' on the passenger instead of reasoning from inertia

6. Question 6 · easy · Newton's laws and momentum

   A physics book lies at rest on a horizontal table. Which pair of forces below is a genuine action-reaction pair according to Newton's third law?

   • A.The weight of the book and the normal force of the table on the book
   • B.The force the book exerts on the table and the normal force the table exerts on the book
   • C.The weight of the book and the force the book exerts on the table
   • D.The normal force on the book and the gravitational pull of the book on the Earth
   Show answer and explanation

   Answer: B. The force the book exerts on the table and the normal force the table exerts on the book

   A third-law pair consists of the two forces of a single interaction, acting on the two different bodies: book pushes table down, table pushes book up.

   Newton's third law pairs always (i) arise from one interaction, (ii) act on two different bodies, and (iii) are of the same type (both contact or both gravitational). The book-table contact interaction gives the pair in option B. Option A is the classic trap: weight (Earth on book) and normal force (table on book) act on the same body and belong to different interactions; they are equal here only because the book is in equilibrium. Options C and D each mix forces from two different interactions. Note the true partner of the book's weight is the book's gravitational pull on the Earth.

   Common mistake: Calling weight and normal force an action-reaction pair because they cancel

7. Question 7 · medium · Newton's laws and momentum

   A ball lies on the smooth floor of a vehicle. Newton's first law, applied to the ball, will hold good (without invoking any pseudo-force) for an observer:

   • A.standing inside a bus that is speeding up on a straight road
   • B.sitting on a merry-go-round rotating at a steady rate
   • C.inside a car in which brakes are being applied
   • D.inside a train moving with uniform velocity on a straight track
   Show answer and explanation

   Answer: D. inside a train moving with uniform velocity on a straight track

   Newton's laws hold in inertial (unaccelerated) frames. Only the train moving with constant velocity qualifies; speeding up, braking, and rotating frames are all accelerated.

   An inertial frame is one moving with constant velocity (including rest). In such a frame a body with zero net force stays at rest or moves uniformly, exactly as the first law demands. The accelerating bus (A) and the braking car (C) have non-zero linear acceleration; the merry-go-round (B) has centripetal acceleration even at constant angular speed. In each of these, the free ball would appear to accelerate without any real force, so the first law fails unless pseudo-forces are introduced. Only the train at uniform velocity (D) is inertial.

   Common mistake: Treating uniform rotation as unaccelerated because the speed is constant

8. Question 8 · easy · Newton's laws and momentum

   A coin is placed on a smooth playing card balanced on top of a glass. The card is flicked away sharply and horizontally. The coin drops straight down into the glass instead of flying off with the card. This happens because:

   • A.The coin is heavier than the card and gravity pulls it down before the card can move
   • B.The sudden flick removes support from under the coin before friction can drag the coin along horizontally with the card
   • C.The card exerts an equal and opposite reaction force that pushes the coin straight down
   • D.Air resistance on the fast-moving card creates a vacuum that sucks the coin down
   Show answer and explanation

   Answer: B. The sudden flick removes support from under the coin before friction can drag the coin along horizontally with the card

   By inertia of rest, the coin tends to stay where it is. The card moves out so quickly that friction has too little time to give the coin any significant horizontal velocity, so gravity alone then pulls the coin straight down.

   Principle: Newton's first law (inertia of rest). A body at rest remains at rest unless a net force acts on it for a sufficient time to change its velocity. The flick is so quick that the (small) frictional force between card and coin has negligible time to impart horizontal momentum to the coin. With the card gone, only gravity acts on the coin, so it falls essentially vertically into the glass. Option A wrongly brings in relative weight, which is irrelevant to the horizontal motion. Option C invents a fictitious downward push. Option D invents an irrelevant aerodynamic mechanism.

   Common mistake: Attributing the effect to the coin's weight rather than to inertia and short contact time

Questions about Laws of Motion for NEET

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Questions are original NEET720 compositions reviewed for correctness, syllabus fit and option quality. Counts update as the bank grows (999 active practice questions in this chapter today).