How much of JEE Main comes from Laws of Motion?

JEEGenie estimates about 4% of JEE Main marks come from Laws of Motion, based on recent papers. The share varies from year to year.

Which formulas matter most in Laws of Motion?

The Laws of Motion sheet on this page has 20 formula entries, starting with Newton's Second Law, Newton's Third Law, Linear Momentum, Impulse, Normal Force. Each one comes with when to use it and the trap to avoid.

What topics does Laws of Motion cover for JEE?

Laws of Motion covers Newton's Laws of Motion, Free Body Diagrams, Friction, Dynamics of Circular Motion, Pseudo Forces.

How should I revise Laws of Motion before the exam?

Learn each formula together with its condition of use, read the trap listed beside it, then practise questions and review every mistake. The practice link on this page opens Laws of Motion questions on JEEGenie.

How many previous-year questions are there on Laws of Motion?

JEEGenie has 341 previous-year questions on Laws of Motion, and this page shows a few with worked explanations.

Is practice on Laws of Motion free on JEEGenie?

Sign-up is free and includes a 7-day Pro trial. After the trial, free accounts keep a limited daily quota.

Laws of Motion for JEE Main & Advanced — formulas, what is asked, and traps

JEEGenie estimates about 4% of JEE Main marks come from Laws of Motion. This page covers 20 formula entries, each with when to use it, what JEE asks and the traps. A common slip: Forgetting that ${\vec{F}}_{net}$ is the vector sum of all forces, not a single force.

Key points to know

Newton's First Law (Law of Inertia). A body continues in its state of rest or uniform motion unless acted upon by an external unbalanced force. It defines inertia and introduces the concept of force.
Newton's Second Law. The net force on a body equals the rate of change of its momentum, i.e., ${\vec{F}}_{net} = m \vec{a}$ for constant mass.
Newton's Third Law. For every action, there is an equal and opposite reaction. Action-reaction pairs act on different bodies.
Inertia and Mass. Inertia is the tendency of a body to resist change in its state of motion. Mass is a measure of inertia.
Linear Momentum. Linear momentum is the product of mass and velocity. It is a vector quantity conserved in the absence of external forces.
Impulse. Impulse is the product of force and time interval, equal to the change in momentum.
Normal Force. The contact force perpendicular to the surface. It adjusts to prevent interpenetration.
Tension. The pulling force transmitted through a string, rope, or cable. It is the same throughout an ideal (massless, inextensible) string.
Friction (Static and Kinetic). Friction opposes relative motion. Static friction ( $f_{s} \leq μ_{s} N$ ) prevents motion; kinetic friction ( $f_{k} = μ_{k} N$ ) opposes sliding.
Centripetal Force. The net force directed toward the center of a circular path, causing centripetal acceleration.
Pseudo Force (Inertial Force). In a non-inertial (accelerating) frame, an imaginary force ${\vec{F}}_{p s e u d o} = - m {\vec{a}}_{f r a m e}$ is added to apply Newton's laws.

Formula sheet

Name	Formula	When to use
Newton's Second Law	${\vec{F}}_{net} = \frac{d \vec{p}}{d t} = m \vec{a}$	Use to relate net force to acceleration for any object with constant mass.
Newton's Third Law	${\vec{F}}_{12} = - {\vec{F}}_{21}$	Use to identify pairs of forces in interactions (e.g., normal force, tension, friction).
Linear Momentum	$\vec{p} = m \vec{v}$	Use to analyze collisions, explosions, and impulse problems.
Impulse	$\vec{J} = \int \vec{F} d t = Δ \vec{p}$	Use when force acts over a short time (e.g., hitting a ball, catching an object).
Normal Force	$N = m g \cos θ$ (on incline) or $N = m g + m a$ (in accelerating lift)	Use in free-body diagrams for objects on surfaces or in contact.
Tension	$T$ (varies with acceleration in connected systems)	Use in problems with strings, pulleys, and connected bodies.
Friction (Static and Kinetic)	$f_{s} \leq μ_{s} N$ , $f_{k} = μ_{k} N$	Use whenever surfaces are in contact and relative motion is possible.
Centripetal Force	$F_{c} = \frac{m v^{2}}{r} = m ω^{2} r$	Use for objects in uniform circular motion (e.g., banked curves, vertical loops).
Pseudo Force (Inertial Force)	${\vec{F}}_{p s e u d o} = - m {\vec{a}}_{f r a m e}$	Use when solving problems from an accelerating frame (e.g., a lift, a car turning).
Solving Connected Systems (Atwood Machine)	$a = \frac{(m_{1} - m_{2}) g}{m_{1} + m_{2}}$ (for simple Atwood)	Use for problems with two or more objects connected by strings over pulleys.
Lami's Theorem	$\frac{F_{1}}{\sin α} = \frac{F_{2}}{\sin β} = \frac{F_{3}}{\sin γ}$	Use for problems with three forces acting at a point (e.g., hanging mass, tension in wires).
Constraint Relations (String Length Constant)	$a_{1} + a_{2} = 0$ (for two blocks on same string over pulley) or more complex relations.	Use in problems with multiple pulleys or moving pulleys.
Banking of Roads (Optimal Speed)	$v_{0} = \sqrt{r g \tan θ}$	Use for problems on banked curves without friction or with friction.
Vertical Circular Motion (Minimum Speed at Top)	$v_{top, min} = \sqrt{g r}$	Use $\sqrt{g r}$ at the top for a mass on a string (or inside a track), where tension/normal force cannot be negative; for a rod/tube/bead on a wire, $v_{t o p} \geq 0$ and $v_{b o t t o m} \geq 2 \sqrt{g r}$ .
Impulse-Momentum Theorem	$\vec{J} = {\vec{p}}_{f} - {\vec{p}}_{i}$	Use when force acts over a short time or when final/initial velocities are known.
Conservation of Linear Momentum	$\sum {\vec{p}}_{i} = \sum {\vec{p}}_{f}$	Use for collisions, explosions, and recoil problems.
Equilibrium of a Particle	$\sum F_{x} = 0$ , $\sum F_{y} = 0$	Use for stationary objects or objects moving with constant velocity.
Spring Force (Hooke's Law)	$F = - k x$	Use for problems involving springs, oscillations, or elastic forces.
Pulley Systems (Movable Pulley)	$a_{load} = \frac{1}{2} a_{effort}$ (for single movable pulley)	Use for problems with block and tackle or complex pulley arrangements.
Friction on Inclined Plane	$f_{s} \leq μ_{s} m g \cos θ$ , $f_{k} = μ_{k} m g \cos θ$	Use for any object on an inclined plane with friction.

Open the Laws of Motion formula page

What JEE asks

Newton's First Law (Law of Inertia). JEE often tests this with conceptual questions about passengers in a moving bus or objects on a frictionless surface.
Newton's Second Law. JEE frequently asks to find acceleration of connected blocks or tension in strings using free-body diagrams.
Newton's Third Law. JEE tests this with questions on walking, rocket propulsion, or recoil of a gun.
Inertia and Mass. Conceptual questions comparing inertia of different objects.
Linear Momentum. JEE often uses momentum conservation in 1D and 2D collisions.
Impulse. JEE asks to find average force from change in momentum or area under F-t curve.
Normal Force. JEE tests with problems on inclined planes, lifts, and circular motion.
Tension. JEE often uses Atwood machines or multiple blocks connected by strings.
Friction (Static and Kinetic). JEE tests with problems on blocks on inclines, wedges, and finding minimum force to move an object.
Centripetal Force. JEE asks for minimum speed at the top of a vertical circle or angle of banking.
Pseudo Force (Inertial Force). JEE tests with problems on a pendulum in an accelerating train or a block on a wedge.
Free-Body Diagram (FBD). JEE expects clear FBDs for multi-body problems; marks often awarded for correct diagrams.
Solving Connected Systems (Atwood Machine). JEE often modifies with inclines or multiple pulleys.
Lami's Theorem. JEE tests with strings supporting a weight or forces on a joint.
Constraint Relations (String Length Constant). JEE often has complex pulley systems requiring constraint equations.
Banking of Roads (Optimal Speed). JEE asks for maximum safe speed on a banked road with friction.
Vertical Circular Motion (Minimum Speed at Top). JEE asks for speed at different points or tension variation.
Impulse-Momentum Theorem. JEE tests with problems on bouncing balls or hitting a bat.
Conservation of Linear Momentum. JEE often combines with energy conservation for elastic collisions.
Equilibrium of a Particle. JEE tests with hanging masses, inclined planes, and concurrent forces.
Spring Force (Hooke's Law). JEE often combines springs with blocks and pulleys.
Pulley Systems (Movable Pulley). JEE tests with systems having multiple pulleys and blocks.
Friction on Inclined Plane. JEE asks for acceleration, minimum angle for sliding, or force to push up.

Common traps

Confusing 'no net force' with 'no force at all' — balanced forces also result in no acceleration. Newton's First Law (Law of Inertia)
Forgetting that ${\vec{F}}_{net}$ is the vector sum of all forces, not a single force. Newton's Second Law
Thinking action-reaction forces cancel each other — they don't because they act on different objects. Newton's Third Law
Assuming heavier objects always fall faster — inertia affects acceleration only via net force. Inertia and Mass
Forgetting that momentum is a vector — direction matters in collisions. Linear Momentum
Using average force when force is not constant — integrate or use area under F-t graph. Impulse
Assuming normal force always equals weight — it doesn't on inclines or in accelerating frames. Normal Force
Assuming tension is the same on both sides of a pulley if the pulley has mass or friction. Tension
Using $f_{s} = μ_{s} N$ when the object is not at the verge of slipping — it's an inequality. Friction (Static and Kinetic)
Thinking centripetal force is a separate force — it's the net radial force from tension, gravity, etc. Centripetal Force
Applying pseudo force in an inertial frame — it's only for accelerating reference frames. Pseudo Force (Inertial Force)
Including forces that the object exerts on others — only forces on the object. Free-Body Diagram (FBD)
Assuming acceleration is g for one block — it's less due to inertia of the other block. Solving Connected Systems (Atwood Machine)
Using it when forces are not concurrent or not in equilibrium. Lami's Theorem

Topics in Laws of Motion

Newton's Laws of Motion
Free Body Diagrams
Friction
Dynamics of Circular Motion
Pseudo Forces

Previous-year questions on Laws of Motion

JEEGenie has 341 previous-year questions on Laws of Motion. A few worked examples follow.

Year	Questions
2026	19
2025	18
2024	35
2023	29
2022	35
2021	37
2020	9
2019	28
2018	8
2017	3
2016	7
2015	3
2014	11
2013	6
2012	6
2011	4
2010	4
2009	2
2008	1
2007	5
2006	3
2005	5
2004	4
2003	8
2002	7
2001	6
2000	3
1997	3
1996	1
1994	1
1993	1
1992	2
1990	1
1989	2
1987	2
1986	3
1985	1
1984	5
1983	1
1981	2
1980	4
1979	1
1978	5

Question 1 easy

A particle is rotating in a circular path and at any instant its motion can be described as

θ = \frac{5 t^{4}}{40} - \frac{t^{3}}{3}

. The angular acceleration of the particle after 10 seconds is _________ rad/s2.

Answer: C

Explanation. Given

θ = \frac{5 t^{4}}{40} - \frac{t^{3}}{3} = \frac{t^{4}}{8} - \frac{t^{3}}{3} .

Angular velocity:

ω = \frac{d θ}{d t} = \frac{4 t^{3}}{8} - t^{2} = \frac{t^{3}}{2} - t^{2} .

Angular acceleration:

α = \frac{d ω}{d t} = \frac{3 t^{2}}{2} - 2 t .

t = 10

α = \frac{3 (10)^{2}}{2} - 2 (10) = \frac{300}{2} - 20 = 150 - 20 = 130.

130

Correct option: **C**.

From NTA/IIT papers: JEE Main 2026 · 2 Apr Shift 1

Question 2 medium

A block of mass 1 kg , moving along

x

with speed

v_{i} = 10 m / s

enters a rough region ranging from

x = 0.1 m

x = 1.9 m

. The retarding force acting on the block in this range is

F_{r} = - k r N

, with k

= 10 N / m

. Then the final speed of the block as it crosses rough region is.

$4 m / s$
$10 m / s$
$8 m / s$
$6 m / s$

Answer: C

Explanation. Work done by retarding force from

x = 0.1

x = 1.9

W = \int_{0.1}^{1.9} - k x d x = - \frac{k}{2} {[x^{2}]}_{0.1}^{1.9}

= - \frac{10}{2} (3.61 - 0.01) = - 5 \times 3.6 = - 18 J

Using work-energy theorem:

\frac{1}{2} m v_{f}^{2} - \frac{1}{2} m v_{i}^{2} = W

\frac{1}{2} (1) v_{f}^{2} - \frac{1}{2} (1) (10^{2}) = - 18

\frac{v_{f}^{2}}{2} - 50 = - 18 ⟹ \frac{v_{f}^{2}}{2} = 32

v_{f}^{2} = 64 ⟹ v_{f} = 8 m / s

The answer is option C.

From NTA/IIT papers: JEE Main 2025 · 3 Apr Shift 2

Question 3 hard

A particle is moving in a circle of radius

50 c m

in such a way that at any instant the normal and tangential components of it's acceleration are equal. If its speed at

t = 0

4 m / s

, the time taken to complete the first revolution will be

\frac{1}{α} [1 - e^{- 2 π}] s

, where

α =

_________.

Answer: 8

Explanation. Given normal and tangential accelerations are equal:

\frac{v^{2}}{R} = \frac{d v}{d t}

Separating variables with

R = 0.5 m

\frac{d v}{v^{2}} = \frac{d t}{R}

Integrating from

v_{0} = 4 m/s

t = 0

- \frac{1}{v} + \frac{1}{4} = \frac{t}{0.5} ⟹ \frac{1}{v} = \frac{1}{4} - 2 t

v = \frac{1}{\frac{1}{4} - 2 t} = \frac{4}{1 - 8 t}

Distance for one revolution:

s = 2 π R = π m

s = \int_{0}^{T} v d t = \int_{0}^{T} \frac{4}{1 - 8 t} d t = - \frac{1}{2} \ln (1 - 8 T)

Setting

s = π

- \frac{1}{2} \ln (1 - 8 T) = π ⟹ 1 - 8 T = e^{- 2 π}

T = \frac{1}{8} (1 - e^{- 2 π})

Comparing with

\frac{1}{α} (1 - e^{- 2 π})

, we get

α = 8

. Answer: 8

From NTA/IIT papers: JEE Main 2024 · 29 Jan Shift 2

Question 4 easy

A monkey of mass

50 k g

climbs on a rope which can withstand the tension (T) of

350 N

. If monkey initially climbs down with an acceleration of

4 m / s^{2}

and then climbs up with an acceleration of

5 m / s^{2}

. Choose the correct option

(g = 10 m / s^{2})

$T = 700 N$ while climbing upward
$T = 350 N$ while going downward
Rope will break while climbing upward
Rope will break while going downward

Answer: C

Explanation. **Principle:** For the monkey on the rope, apply Newton's second law. Tension acts upward, weight

m g

acts downward. Mass

m = 50 k g

g = 10 m / s^{2}

, so weight

m g = 500 N

. **Case 1: Climbing down with

a = 4 m / s^{2}

** Taking downward as positive:

m g - T = m a

T = m (g - a) = 50 (10 - 4) = 300 N

Since

300 N < 350 N

, the rope does not break while going downward. So (D) is wrong, and (B) is wrong because

T = 300 N

, not

350 N

. **Case 2: Climbing up with

a = 5 m / s^{2}

** Taking upward as positive:

T - m g = m a

T = m (g + a) = 50 (10 + 5) = 750 N

Since

750 N > 350 N

, the rope breaks while climbing upward. Thus (C) is correct. Option (A) is wrong because

T = 750 N

, not

700 N

. Answer: (C)

From NTA/IIT papers: JEE Main 2022 · 26 Jul Shift 1

Frequently asked questions

How much of JEE Main comes from Laws of Motion?: JEEGenie estimates about 4% of JEE Main marks come from Laws of Motion, based on recent papers. The share varies from year to year.
Which formulas matter most in Laws of Motion?: The Laws of Motion sheet on this page has 20 formula entries, starting with Newton's Second Law, Newton's Third Law, Linear Momentum, Impulse, Normal Force. Each one comes with when to use it and the trap to avoid.
What topics does Laws of Motion cover for JEE?: Laws of Motion covers Newton's Laws of Motion, Free Body Diagrams, Friction, Dynamics of Circular Motion, Pseudo Forces.
How should I revise Laws of Motion before the exam?: Learn each formula together with its condition of use, read the trap listed beside it, then practise questions and review every mistake. The practice link on this page opens Laws of Motion questions on JEEGenie.
How many previous-year questions are there on Laws of Motion?: JEEGenie has 341 previous-year questions on Laws of Motion, and this page shows a few with worked explanations.
Is practice on Laws of Motion free on JEEGenie?: Sign-up is free and includes a 7-day Pro trial. After the trial, free accounts keep a limited daily quota.