1.Easy
A 1400 kg car moving at 11 m/s runs into a stationary 700 kg car. The cars lock together. Find their common velocity v′ just after the collision (positive in the first car’s direction).
m1 = 1400 kgv1 = 11 m/sm2 = 700 kgv2 = 0 m/s
v′ = m/s
Momentum & collisions worksheet with answers
2.Easy
A 4 kg trolley moving at 10 m/s runs into a 4.5 kg trolley at rest. After the collision the first trolley continues in the same direction at 4 m/s. Find the velocity v′2 of the second trolley.
m1 = 4 kgv1 = 10 m/sm2 = 4.5 kgv′1 = 4 m/s
v′2 = m/s
3.Medium
A 1 kg glider moving at 7 m/s makes a perfectly elastic head-on collision with a 4.5 kg glider at rest on a frictionless track. Find the velocity v′1 of the first glider after the collision (positive in its original direction).
m1 = 1 kgm2 = 4.5 kgv1 = 7 m/sv2 = 0
v′1 = m/s
4.Medium
An 8 g bullet is fired horizontally into a 1 kg wooden block hanging on light strings, and stays inside it. The block swings up until it is 18 cm higher than at the start. Use g = 9.81 m/s². Find the speed v of the bullet before impact.
m = 8 gM = 1 kgh = 18 cmg = 9.81 m/s²
v = m/s
5.Hard
A 0.2 kg ball hits a wall at 15 m/s and bounces straight back at 6 m/s. The contact lasts 50 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.2 kgvin = 15 m/svout = 6 m/sΔt = 50 ms
J = N·s
6.Hard
A 1200 kg car runs into a parked 1400 kg car. The wrecks lock together and skid 18 m before stopping. The coefficient of kinetic friction between tyres and road is 0.8. Use g = 9.81 m/s². Find the speed v1 of the first car just before the collision.
m1 = 1200 kgm2 = 1400 kgd = 18 mμ = 0.8g = 9.81 m/s²
v1 = m/s
Answer key
- 1. v′ = 7.333 m/s
- 2. v′2 = 5.333 m/s
- 3. v′1 = −4.455 m/s
- 4. v = 236.8 m/s
- 5. J = 4.2 N·s
- 6. v1 = 36.42 m/s
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