Inertia — JEE Main Physics MCQs with Solutions
Free JEE Main Physics Inertia MCQs with step-by-step solutions (38 questions). Part of Laws of Motion. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Inertia · easy · numerical
Momentum, the measure of inertia of motion, of a $2$ kg body moving at $5$ m/s is
A. $7$ kg·m/s
B. $0.4$ kg·m/s
C. $2.5$ kg·m/s
D. $10$ kg·m/s ✓ Correct
Solution: $p = mv = 2 \times 5 = 10$ kg·m/s.
Q2 — Inertia · easy · numerical
The momentum of a $0.5$ kg ball moving at $20$ m/s is
A. $0.025$ kg·m/s
B. $40$ kg·m/s
C. $20.5$ kg·m/s
D. $10$ kg·m/s ✓ Correct
Solution: $p = 0.5 \times 20 = 10$ kg·m/s.
Q3 — Inertia · easy · theory
Which body has GREATER inertia: a $2$ kg or a $5$ kg body?
A. Both equal
B. The $2$ kg body
C. Cannot say
D. The $5$ kg body ✓ Correct
Solution: Inertia is measured by mass; the $5$ kg body has more mass, hence more inertia.
Q4 — Inertia · easy · numerical
A body has momentum $30$ kg·m/s and mass $3$ kg. Its velocity is
A. $10$ m/s ✓ Correct
B. $27$ m/s
C. $90$ m/s
D. $0.1$ m/s
Solution: $v = p/m = 30/3 = 10$ m/s.
Q5 — Inertia · easy · numerical
A body has momentum $40$ kg·m/s at a velocity of $8$ m/s. Its mass is
A. $0.2$ kg
B. $48$ kg
C. $320$ kg
D. $5$ kg ✓ Correct
Solution: $m = p/v = 40/8 = 5$ kg.
Q6 — Inertia · easy · numerical
A body moves at a constant velocity of $10$ m/s with no external force. By the law of inertia, its velocity after $5$ s is
A. $2$ m/s
B. $10$ m/s ✓ Correct
C. Zero
D. $50$ m/s
Solution: With no net force, Newton's first law keeps the velocity unchanged at $10$ m/s.
Q7 — Inertia · easy · numerical
The momentum of a $1000$ kg car moving at $20$ m/s is
A. $20000$ kg·m/s ✓ Correct
B. $50$ kg·m/s
C. $2000$ kg·m/s
D. $1020$ kg·m/s
Solution: $p = 1000 \times 20 = 20000$ kg·m/s.
Q8 — Inertia · medium · numerical
Two bodies of masses $3$ kg and $6$ kg move at the same velocity. The ratio of their momenta (inertia of motion) is
A. $1:2$ ✓ Correct
B. $1:1$
C. $2:1$
D. $1:4$
Solution: At equal $v$, $p \propto m$, so ratio $= 3:6 = 1:2$.
Q9 — Inertia · easy · numerical
The momentum of a $0.2$ kg ball moving at $15$ m/s is
A. $0.013$ kg·m/s
B. $3$ kg·m/s ✓ Correct
C. $30$ kg·m/s
D. $75$ kg·m/s
Solution: $p = 0.2 \times 15 = 3$ kg·m/s.
Q10 — Inertia · easy · numerical
A body of mass $2$ kg has momentum $8$ kg·m/s. Its velocity is
A. $4$ m/s ✓ Correct
B. $10$ m/s
C. $16$ m/s
D. $0.25$ m/s
Solution: $v = 8/2 = 4$ m/s.
Q11 — Inertia · medium · numerical
A truck ($5000$ kg) and a car ($1000$ kg) move at the same speed. The ratio of their momenta is
A. $25:1$
B. $1:5$
C. $5:1$ ✓ Correct
D. $1:1$
Solution: At equal $v$, $p \propto m$: $5000:1000 = 5:1$.
Q12 — Inertia · medium · numerical
A $3$ kg body moves with uniform velocity. The net force on it is
A. $10$ N
B. $30$ N
C. $3$ N
D. Zero ✓ Correct
Solution: Uniform velocity means no acceleration, so by inertia the net force is zero.
Q13 — Inertia · easy · theory
If the velocity of a $2$ kg body increases from $5$ m/s to $10$ m/s, its momentum changes from
A. $2$ to $4$ kg·m/s
B. $20$ to $10$ kg·m/s
C. $5$ to $10$ kg·m/s
D. $10$ to $20$ kg·m/s ✓ Correct
Solution: $p_1 = 10$, $p_2 = 20$ kg·m/s — momentum doubles as velocity doubles.
Q14 — Inertia · easy · numerical
A cricket ball of mass $0.15$ kg moves at $20$ m/s. Its momentum is
A. $133$ kg·m/s
B. $3$ kg·m/s ✓ Correct
C. $0.0075$ kg·m/s
D. $20.15$ kg·m/s
Solution: $p = 0.15 \times 20 = 3$ kg·m/s.
Q15 — Inertia · easy · numerical
Two bodies have equal momentum $12$ kg·m/s. One is $2$ kg moving at $6$ m/s; the other is $4$ kg. Its velocity is
A. $48$ m/s
B. $6$ m/s
C. $2$ m/s
D. $3$ m/s ✓ Correct
Solution: $v = p/m = 12/4 = 3$ m/s.
Q16 — Inertia · easy · theory
Which has greater inertia: a $10$ kg block or a $100$ g ball?
A. The $100$ g ball
B. Both equal
C. The $10$ kg block ✓ Correct
D. Depends on velocity
Solution: $10$ kg $= 100 \times 0.1$ kg, so the block has $100$ times more mass and inertia.
Q17 — Inertia · easy · numerical
A body of momentum $100$ kg·m/s has a mass of $20$ kg. Its velocity is
A. $5$ m/s ✓ Correct
B. $0.2$ m/s
C. $2000$ m/s
D. $80$ m/s
Solution: $v = 100/20 = 5$ m/s.
Q18 — Inertia · easy · numerical
A $2000$ kg truck moving at $15$ m/s has momentum
A. $2015$ kg·m/s
B. $3000$ kg·m/s
C. $30000$ kg·m/s ✓ Correct
D. $133$ kg·m/s
Solution: $p = 2000 \times 15 = 30000$ kg·m/s.
Q19 — Inertia · easy · theory
A body moves with uniform velocity $8$ m/s (no force). By inertia, the distance covered in $3$ s is
A. $8$ m
B. $11$ m
C. $24$ m ✓ Correct
D. $2.67$ m
Solution: Constant velocity: $s = vt = 8 \times 3 = 24$ m.
Q20 — Inertia · easy · numerical
A $4$ kg object has momentum $24$ kg·m/s. Its velocity is
A. $6$ m/s ✓ Correct
B. $20$ m/s
C. $0.17$ m/s
D. $96$ m/s
Solution: $v = 24/4 = 6$ m/s.
Q21 — Inertia · easy · numerical
A $12$ kg body moves at $2.5$ m/s. Its momentum is
A. $60$ kg·m/s
B. $4.8$ kg·m/s
C. $30$ kg·m/s ✓ Correct
D. $14.5$ kg·m/s
Solution: $p = 12 \times 2.5 = 30$ kg·m/s.
Q22 — Inertia · easy · theory
A stationary $8$ kg body has no net force acting. By the law of inertia it will
A. Accelerate
B. Start moving
C. Remain at rest ✓ Correct
D. Move backward
Solution: A body at rest stays at rest unless acted on by a net force (Newton's first law).
Q23 — Inertia · easy · numerical
A body of momentum $45$ kg·m/s moving at $9$ m/s has mass
A. $54$ kg
B. $405$ kg
C. $0.2$ kg
D. $5$ kg ✓ Correct
Solution: $m = 45/9 = 5$ kg.
Q24 — Inertia · easy · numerical
A $1500$ kg car moving at $12$ m/s has momentum
A. $125$ kg·m/s
B. $1512$ kg·m/s
C. $1800$ kg·m/s
D. $18000$ kg·m/s ✓ Correct
Solution: $p = 1500 \times 12 = 18000$ kg·m/s.
Q25 — Inertia · easy · theory
Two bodies of equal mass $3$ kg move at $10$ m/s and rest respectively. Their INERTIA (mass) is
A. Greater for the resting one
B. Greater for the moving one
C. Zero for the resting one
D. Equal for both ✓ Correct
Solution: Inertia depends only on mass; both have $3$ kg, so equal inertia (their momenta differ).
Q26 — Inertia · easy · numerical
A body of mass $0.25$ kg moves at $8$ m/s. Its momentum is
A. $32$ kg·m/s
B. $8.25$ kg·m/s
C. $0.031$ kg·m/s
D. $2$ kg·m/s ✓ Correct
Solution: $p = 0.25 \times 8 = 2$ kg·m/s.
Q27 — Inertia · easy · numerical
A $20$ kg body has momentum $60$ kg·m/s. Its velocity is
A. $40$ m/s
B. $1200$ m/s
C. $0.33$ m/s
D. $3$ m/s ✓ Correct
Solution: $v = 60/20 = 3$ m/s.
Q28 — Inertia · easy · numerical
A $3$ kg ball is thrown at $7$ m/s. Its momentum is
A. $21$ kg·m/s ✓ Correct
B. $10$ kg·m/s
C. $49$ kg·m/s
D. $2.33$ kg·m/s
Solution: $p = 3 \times 7 = 21$ kg·m/s.
Q29 — Inertia · easy · numerical
A body of mass $100$ g moves at $50$ m/s. Its momentum is
A. $50.1$ kg·m/s
B. $5$ kg·m/s ✓ Correct
C. $0.5$ kg·m/s
D. $5000$ kg·m/s
Solution: $m = 0.1$ kg; $p = 0.1 \times 50 = 5$ kg·m/s.
Q30 — Inertia · easy · theory
A $50$ kg passenger sits in a bus moving at $10$ m/s. When the bus stops suddenly, by inertia of motion the passenger tends to
A. Move sideways
B. Stay still
C. Fall backward
D. Lurch forward at about $10$ m/s ✓ Correct
Solution: The body tends to keep its forward velocity of $10$ m/s while the bus decelerates.