Inelastic Collision — IISER Physics MCQs with Solutions
Free IISER Physics Inelastic Collision MCQs with step-by-step solutions (20 questions). Part of Collision. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Inelastic Collision · easy · numerical
A 4 kg glider moving at 9 m/s on a frictionless air track collides with a stationary 8 kg glider and the two couple together. Find their common speed just after the collision.
A. 6 m/s
B. 2 m/s
C. 3 m/s ✓ Correct
D. 4.5 m/s
Solution: Momentum conservation gives v = m₁u/(m₁+m₂) = 4×9/12 = 3 m/s.
Q2 — Inelastic Collision · easy · numerical
A 5 kg trolley moving at 12 m/s on a smooth horizontal track collides with a stationary 10 kg trolley and sticks to it. What is the speed of the combination just after impact?
A. 8 m/s
B. 6 m/s
C. 4 m/s ✓ Correct
D. 3 m/s
Solution: v = m₁u/(m₁+m₂) = 5×12/15 = 4 m/s, since the total momentum 60 kg·m/s is shared by 15 kg.
Q3 — Inelastic Collision · easy · numerical
A 6 kg puck sliding at 12 m/s on frictionless ice hits a stationary 2 kg puck and the two move off together. Find their common speed.
A. 9 m/s ✓ Correct
B. 4.5 m/s
C. 6 m/s
D. 12 m/s
Solution: v = m₁u/(m₁+m₂) = 6×12/8 = 72/8 = 9 m/s by conservation of momentum.
Q4 — Inelastic Collision · easy · numerical
A 4 kg cart moving at 15 m/s catches up with an 8 kg cart moving at 6 m/s in the same direction on a smooth track. They collide and lock together. Find their common speed after the collision.
A. 12 m/s
B. 9 m/s ✓ Correct
C. 10.5 m/s
D. 7.5 m/s
Solution: v = (4×15 + 8×6)/(4+8) = 108/12 = 9 m/s; total momentum 108 kg·m/s is conserved.
Q5 — Inelastic Collision · easy · numerical
A 6 kg sphere moving at 5 m/s collides head-on with a 4 kg sphere moving at 10 m/s in the opposite direction. They stick together on impact. Find the velocity of the combined mass just after the collision.
A. 1 m/s, in the direction the 6 kg sphere was moving
B. 1 m/s, in the direction the 4 kg sphere was moving ✓ Correct
C. 3 m/s, in the direction the 4 kg sphere was moving
D. 7 m/s, in the direction the 6 kg sphere was moving
Solution: Taking the 6 kg sphere's direction as positive, v = (6×5 − 4×10)/10 = −10/10 = −1 m/s, i.e. 1 m/s along the 4 kg sphere's original direction.
Q6 — Inelastic Collision · easy · numerical
A 2 kg glider moving at 10 m/s and a 5 kg glider moving at 4 m/s approach each other head-on on a frictionless air track. They collide and couple together. What is their speed just after the collision?
A. 2 m/s
B. 0 m/s ✓ Correct
C. 7 m/s
D. 4 m/s
Solution: The net momentum is 2×10 − 5×4 = 0, so the coupled gliders come to rest: v = 0/7 = 0 m/s.
Q7 — Inelastic Collision · easy · numerical
A 50 g pellet moving horizontally at 200 m/s embeds itself in a 1.95 kg cart resting on a smooth horizontal track. Find the speed of the cart (with the pellet) just after the impact.
A. 2.5 m/s
B. 10 m/s
C. 5 m/s ✓ Correct
D. 4 m/s
Solution: Momentum conservation: 0.05×200 = (0.05 + 1.95)v, so v = 10/2 = 5 m/s.
Q8 — Inelastic Collision · easy · numerical
A 10 kg cart moving at 6 m/s collides with a stationary 2 kg cart and the two stick together. How much kinetic energy is lost in the collision?
A. 60 J
B. 180 J
C. 150 J
D. 30 J ✓ Correct
Solution: v = 10×6/12 = 5 m/s, so KE falls from ½×10×6² = 180 J to ½×12×5² = 150 J, a loss of 30 J.
Q9 — Inelastic Collision · medium · numerical
A 6 kg puck moving at 15 m/s on frictionless ice strikes a stationary 12 kg puck and sticks to it. What percentage of the initial kinetic energy is lost in the collision?
A. 75%
B. 33.3%
C. 50%
D. 66.7% ✓ Correct
Solution: Fraction lost = m₂/(m₁+m₂) = 12/18 = 2/3 ≈ 66.7%; explicitly v = 90/18 = 5 m/s, so KE drops from 675 J to ½×18×25 = 225 J.
Q10 — Inelastic Collision · medium · numerical
On frictionless ice, a 3 kg puck moving east at 7 m/s collides with a 4 kg puck moving north at 7 m/s. The two stick together. Find the speed of the combined mass just after the collision.
A. 5 m/s ✓ Correct
B. 3.5 m/s
C. 7 m/s
D. 4 m/s
Solution: The momenta are p = (3×7, 4×7) = (21, 28) kg·m/s, so |p| = √(21² + 28²) = 35 kg·m/s and v = 35/7 = 5 m/s.
Q11 — Inelastic Collision · medium · numerical
A 25 g pellet moving horizontally at 400 m/s embeds itself in a 4.975 kg wooden block hanging from light strings (a ballistic pendulum). To what height does the block rise? (g = 10 m/s²)
A. 0.4 m
B. 0.2 m ✓ Correct
C. 0.1 m
D. 0.8 m
Solution: The block-pellet system moves off at v = 0.025×400/5 = 2 m/s, and rises h = v²/2g = 4/20 = 0.2 m.
Q12 — Inelastic Collision · medium · numerical
A 3 kg glider moving at 16 m/s on a frictionless air track collides with a stationary 5 kg glider and the two couple together. Find the kinetic energy of the combination just after the collision.
A. 384 J
B. 96 J
C. 240 J
D. 144 J ✓ Correct
Solution: v = 3×16/8 = 6 m/s, so KE = ½×8×6² = 144 J (down from the initial ½×3×16² = 384 J).
Q13 — Inelastic Collision · medium · numerical
A 6 kg trolley moving at 9 m/s collides with a stationary 3 kg trolley on a smooth track and the two stick together. Find the magnitude of the impulse delivered to the 3 kg trolley during the collision.
A. 36 N·s
B. 27 N·s
C. 18 N·s ✓ Correct
D. 54 N·s
Solution: The common velocity is v = 6×9/9 = 6 m/s, so the impulse on the 3 kg trolley is its momentum change, 3×6 − 0 = 18 N·s.
Q14 — Inelastic Collision · medium · numerical
A 5 kg cart moving at 8 m/s and a 3 kg cart moving at 8 m/s approach each other head-on on a smooth track. They collide and stick together. How much mechanical energy is converted to heat in the collision?
A. 120 J
B. 16 J
C. 256 J
D. 240 J ✓ Correct
Solution: v = (5×8 − 3×8)/8 = 2 m/s, so KE falls from ½×5×64 + ½×3×64 = 256 J to ½×8×4 = 16 J: 240 J is dissipated.
Q15 — Inelastic Collision · medium · numerical
A cart moving at 12 m/s collides with a stationary 4 kg cart on a smooth track. The two stick together and move at 9 m/s. Find the mass of the moving cart.
A. 12 kg ✓ Correct
B. 9 kg
C. 8 kg
D. 6 kg
Solution: Momentum conservation: 12m = 9(m + 4), so 3m = 36 and m = 12 kg.
Q16 — Inelastic Collision · medium · numerical
A 2 kg puck slides on frictionless ice and hits a stationary 6 kg puck. The two stick together and move off at 5 m/s. What was the initial speed of the 2 kg puck?
A. 12.5 m/s
B. 25 m/s
C. 15 m/s
D. 20 m/s ✓ Correct
Solution: Momentum conservation: 2u = (2 + 6)×5 = 40, so u = 20 m/s.
Q17 — Inelastic Collision · medium · numerical
A 3 kg trolley moving at 18 m/s catches up with a 6 kg trolley moving at 9 m/s in the same direction and locks onto it. How much kinetic energy is lost in the collision?
A. 81 J ✓ Correct
B. 648 J
C. 162 J
D. 729 J
Solution: v = (3×18 + 6×9)/9 = 108/9 = 12 m/s, so KE drops from ½×3×18² + ½×6×9² = 486 + 243 = 729 J to ½×9×12² = 648 J, a loss of 81 J.
Q18 — Inelastic Collision · medium · numerical
A 3 kg sphere moving at 10 m/s collides with a stationary 12 kg sphere and sticks to it. What percentage of the initial kinetic energy remains as kinetic energy after the collision?
A. 40%
B. 25%
C. 20% ✓ Correct
D. 80%
Solution: Fraction retained = m₁/(m₁+m₂) = 3/15 = 20%; explicitly v = 30/15 = 2 m/s, so KE falls from 150 J to ½×15×4 = 30 J.
Q19 — Inelastic Collision · medium · numerical
A 4 kg glider moving at 6 m/s and a 2 kg glider moving at 6 m/s approach each other head-on on a frictionless air track and stick together on impact. Find the magnitude of the impulse each glider exerts on the other.
A. 8 N·s
B. 12 N·s
C. 24 N·s
D. 16 N·s ✓ Correct
Solution: v = (4×6 − 2×6)/6 = 2 m/s, so the 2 kg glider's momentum changes from −12 to +4 kg·m/s: impulse = 2×(2 − (−6)) = 16 N·s.
Q20 — Inelastic Collision · medium · numerical
An 8 kg trolley rolls at 5 m/s along a smooth horizontal track. A 2 kg sack is dropped gently (vertically) into the trolley and stays in it. Find the speed of the trolley afterwards.
A. 4 m/s ✓ Correct
B. 6 m/s
C. 5 m/s
D. 3.2 m/s
Solution: Horizontal momentum is conserved: 8×5 = (8 + 2)v, so v = 40/10 = 4 m/s.