Laws of Motion

What you'll learn

Inertia, F = ma, and action–reaction — the three laws that explain all everyday motion.

This chapter has

Laws of Motion — solved practice questions

6 JEE Physics questions with step-by-step solutions. Attempt each, then reveal the answer.

1. Q1easy

   Newton's first law of motion is also known as the law of:

   • Ainertia
   • Bacceleration
   • Caction-reaction
   • Dgravitation
   Show answer & solution

   Correct answer: (A) inertia

   The first law (a body stays at rest/uniform motion unless acted on by a force) is the law of inertia.

2. Q2easy

   Newton's second law gives the relation:

   • AF = ma
   • BF = mv
   • CF = m/a
   • DF = ma²
   Show answer & solution

   Correct answer: (A) F = ma

   Force = mass × acceleration, i.e. F = ma.

3. Q3easy

   'Every action has an equal and opposite reaction' is Newton's:

   • Afirst law
   • Bsecond law
   • Cthird law
   • Dzeroth law
   Show answer & solution

   Correct answer: (C) third law

   This is Newton's third law of motion.

4. Q4medium

   The momentum of a body is given by:

   • Amv
   • Bma
   • Cm/v
   • Dv/m
   Show answer & solution

   Correct answer: (A) mv

   Momentum p = mass × velocity = mv.

5. Q5medium

   A body of mass 2 kg has an acceleration of 5 m/s². The force acting on it is:

   • A2.5 N
   • B10 N
   • C7 N
   • D3 N
   Show answer & solution

   Correct answer: (B) 10 N

   F = ma = 2 × 5 = 10 N.

6. Q6hard

   The rate of change of momentum of a body is equal to the:

   • Aapplied force
   • Bmass
   • Cvelocity
   • Dacceleration
   Show answer & solution

   Correct answer: (A) applied force

   Newton's second law (in momentum form): the net applied force equals the rate of change of momentum.

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