Inelastic Collision — JEE Main Physics MCQs with Solutions
Free JEE Main Physics Inelastic Collision MCQs with step-by-step solutions (20 questions). Part of Collision. Practise online on Prepizo — no login needed.
▶ Practise Inelastic Collision online (free)
Questions with solutions
Q1 — Inelastic Collision · easy · numerical
A 4 kg body moving at 15 m/s collides with a stationary 6 kg body and the two stick together. Find their common velocity after the collision.
A. 6 m/s ✓ Correct
B. 9 m/s
C. 4 m/s
D. 15 m/s
Solution: Momentum conservation: 4 × 15 = (4 + 6)v, so v = 60/10 = 6 m/s.
Q2 — Inelastic Collision · easy · numerical
A 6 kg trolley moving at 10 m/s catches up with a 4 kg trolley moving at 5 m/s in the same direction and couples with it. Find the common velocity of the pair.
A. 5 m/s
B. 8 m/s ✓ Correct
C. 7.5 m/s
D. 10 m/s
Solution: v = (6 × 10 + 4 × 5)/(6 + 4) = 80/10 = 8 m/s.
Q3 — Inelastic Collision · easy · numerical
An 8 kg body moving at 6 m/s towards the east collides head-on with a 4 kg body moving at 12 m/s towards the west, and they stick together. Find their velocity after the collision.
A. 2 m/s east
B. 4 m/s west
C. 0 m/s (they come to rest) ✓ Correct
D. 6 m/s east
Solution: Total momentum = 8 × 6 - 4 × 12 = 48 - 48 = 0, so the combined 12 kg mass is at rest after the collision.
Q4 — Inelastic Collision · easy · numerical
A 5 kg body moving at 8 m/s meets a 3 kg body moving at 8 m/s in the opposite direction; they stick together on impact. Find their common velocity.
A. 1 m/s in the direction of the 3 kg body
B. 8 m/s in the direction of the 5 kg body
C. 4 m/s in the direction of the 5 kg body
D. 2 m/s in the direction of the 5 kg body ✓ Correct
Solution: v = (5 × 8 - 3 × 8)/(5 + 3) = 16/8 = 2 m/s, along the initial motion of the heavier (5 kg) body.
Q5 — Inelastic Collision · easy · numerical
A 50 g bullet moving at 200 m/s embeds itself in a 950 g wooden block resting on a frictionless table. Find the speed of the block with the bullet inside.
A. 20 m/s
B. 5 m/s
C. 10 m/s ✓ Correct
D. 200 m/s
Solution: Momentum: 0.05 × 200 = (0.05 + 0.95)v, so v = 10/1.0 = 10 m/s.
Q6 — Inelastic Collision · easy · numerical
A 3 kg trolley moving at 12 m/s catches up with a 6 kg trolley moving at 3 m/s in the same direction, and they couple together. Find their common velocity.
A. 7.5 m/s
B. 4.5 m/s
C. 9 m/s
D. 6 m/s ✓ Correct
Solution: v = (3 × 12 + 6 × 3)/(3 + 6) = 54/9 = 6 m/s.
Q7 — Inelastic Collision · medium · numerical
A 4 kg body moving at 9 m/s strikes a stationary 8 kg body and sticks to it. Find the kinetic energy lost in the collision.
A. 108 J ✓ Correct
B. 81 J
C. 54 J
D. 162 J
Solution: Common velocity v = 36/12 = 3 m/s. KE before = ½ × 4 × 9² = 162 J, KE after = ½ × 12 × 3² = 54 J, so the loss is 162 - 54 = 108 J.
Q8 — Inelastic Collision · medium · numerical
A 6 kg body moving at 5 m/s meets a 3 kg body moving at 4 m/s in the opposite direction, and the two stick together. How much heat is generated (kinetic energy lost) in the collision?
A. 45 J
B. 81 J ✓ Correct
C. 99 J
D. 18 J
Solution: v = (30 - 12)/9 = 2 m/s. KE before = 75 + 24 = 99 J, KE after = ½ × 9 × 2² = 18 J, so the loss is 99 - 18 = 81 J.
Q9 — Inelastic Collision · medium · numerical
A 2 kg body moving at 9 m/s towards the east collides at a right angle with a 4 kg body moving at 6 m/s towards the north, and they stick together. Find the speed of the combined mass.
A. 5 m/s ✓ Correct
B. 3 m/s
C. 7.5 m/s
D. 15 m/s
Solution: The momenta are 18 kg·m/s east and 24 kg·m/s north, so total p = √(18² + 24²) = 30 kg·m/s and v = 30/(2 + 4) = 5 m/s.
Q10 — Inelastic Collision · medium · numerical
A 3 kg body moving at 3 m/s towards the east collides perpendicularly with a 2 kg body moving at 6 m/s towards the north, and the two move together after impact. Find their common speed.
A. 4.5 m/s
B. 5 m/s
C. 3 m/s ✓ Correct
D. 2.4 m/s
Solution: p = √(9² + 12²) = 15 kg·m/s, so v = 15/(3 + 2) = 3 m/s.
Q11 — Inelastic Collision · medium · numerical
A 40 g bullet is fired into a 1.96 kg block hanging from long strings; the bullet embeds and the block rises 0.2 m. Take g = 10 m/s². Find the speed of the bullet before impact.
A. 98 m/s
B. 50 m/s
C. 200 m/s
D. 100 m/s ✓ Correct
Solution: Common speed after impact = √(2gh) = √(2 × 10 × 0.2) = 2 m/s; momentum then gives 0.04 × u = 2.0 × 2, so u = 100 m/s.
Q12 — Inelastic Collision · medium · numerical
A 20 g bullet moving at 450 m/s embeds itself in a 2.98 kg block suspended as a ballistic pendulum. Take g = 10 m/s². To what height does the block with the bullet rise?
A. 0.3 m
B. 0.2 m
C. 0.9 m
D. 0.45 m ✓ Correct
Solution: Common speed = 0.02 × 450 / 3.0 = 3 m/s, and h = v²/2g = 9/20 = 0.45 m.
Q13 — Inelastic Collision · medium · numerical
A 6 kg body moving at 15 m/s collides with a stationary 4 kg body and the two stick together. What percentage of the initial kinetic energy is lost?
A. 50%
B. 40% ✓ Correct
C. 20%
D. 60%
Solution: For sticking onto a stationary target the fraction lost is m₂/(m₁ + m₂) = 4/10 = 40%. (Check: v = 9 m/s, KE drops from 675 J to 405 J.)
Q14 — Inelastic Collision · medium · numerical
A 2 kg ball moving at 12 m/s hits a stationary 6 kg block and sticks to it. Find the kinetic energy of the combination just after the collision.
A. 36 J ✓ Correct
B. 108 J
C. 144 J
D. 72 J
Solution: v = 24/8 = 3 m/s, so KE = ½ × 8 × 3² = 36 J (down from the initial 144 J).
Q15 — Inelastic Collision · medium · numerical
An 8 kg shell moving at 5 m/s explodes into two fragments of 6 kg and 2 kg. The 6 kg fragment moves at 8 m/s along the original direction. Find the velocity of the 2 kg fragment.
A. 4 m/s opposite to the original motion ✓ Correct
B. 2 m/s along the original motion
C. 4 m/s along the original motion
D. 8 m/s opposite to the original motion
Solution: Momentum conservation: 8 × 5 = 6 × 8 + 2v, so 2v = 40 - 48 = -8 and v = -4 m/s, i.e. 4 m/s opposite to the original motion.
Q16 — Inelastic Collision · medium · numerical
A 3 kg body moving at 12 m/s hits a stationary 6 kg block and sticks to it. Find the magnitude of the impulse received by the 6 kg block during the collision.
A. 36 N·s
B. 24 N·s ✓ Correct
C. 18 N·s
D. 12 N·s
Solution: Common velocity v = 36/9 = 4 m/s, so the impulse on the block equals its momentum change: 6 × 4 - 0 = 24 N·s.
Q17 — Inelastic Collision · medium · numerical
A 4 kg body moving at 6 m/s towards the east collides head-on with a 2 kg body moving at 6 m/s towards the west, and they stick together. Find the kinetic energy lost in the collision.
A. 48 J
B. 96 J ✓ Correct
C. 12 J
D. 108 J
Solution: v = (24 - 12)/6 = 2 m/s. KE before = 72 + 36 = 108 J, KE after = ½ × 6 × 2² = 12 J, so 108 - 12 = 96 J is lost.
Q18 — Inelastic Collision · medium · numerical
An 8 kg wagon moving at 6 m/s catches up with a 4 kg wagon moving at 3 m/s in the same direction, and they couple together. How much kinetic energy is lost in the coupling?
A. 162 J
B. 150 J
C. 12 J ✓ Correct
D. 24 J
Solution: v = (48 + 12)/12 = 5 m/s; KE drops from 144 + 18 = 162 J to ½ × 12 × 5² = 150 J, a loss of 12 J (equal to ½ × μ × Δu² = ½ × 8/3 × 9).
Q19 — Inelastic Collision · medium · numerical
A 50 g bullet moving at 180 m/s embeds itself in a stationary 450 g block on a smooth surface. What percentage of the kinetic energy of the bullet is converted to heat?
A. 50%
B. 81%
C. 90% ✓ Correct
D. 10%
Solution: Fraction lost = M/(m + M) = 0.45/0.50 = 90%. (Check: v = 9/0.5 = 18 m/s, so KE falls from 810 J to ½ × 0.5 × 18² = 81 J.)
Q20 — Inelastic Collision · medium · numerical
A 4 kg body moving at 10 m/s strikes a stationary 6 kg block and sticks to it; the collision lasts 0.2 s. Find the average force exerted on the 6 kg block during the collision.
A. 200 N
B. 240 N
C. 120 N ✓ Correct
D. 60 N
Solution: Common velocity v = 40/10 = 4 m/s, so the block gains momentum 6 × 4 = 24 kg·m/s, and F = Δp/Δt = 24/0.2 = 120 N.