1.Easy
A 5 kg rifle, free to move, fires a 15 g bullet at 450 m/s. Both start at rest. Find the recoil speed V of the rifle.
M = 5 kgm = 15 gv = 450 m/s
V = m/s
Momentum & collisions worksheet with answers
2.Easy
A 600 kg car moving at 13 m/s runs into a stationary 2000 kg car. The cars lock together. Find their common velocity v′ just after the collision (positive in the first car’s direction).
m1 = 600 kgv1 = 13 m/sm2 = 2000 kgv2 = 0 m/s
v′ = m/s
3.Medium
A 5 kg glider moving at 8 m/s makes a perfectly elastic head-on collision with a 4 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 = 5 kgm2 = 4 kgv1 = 8 m/sv2 = 0
v′1 = m/s
4.Medium
A 5 kg glider moving at 4 m/s makes a perfectly elastic head-on collision with a 2 kg glider at rest on a frictionless track. Find the velocity v′2 of the second glider after the collision.
m1 = 5 kgm2 = 2 kgv1 = 4 m/sv2 = 0
v′2 = m/s
5.Hard
A 0.2 kg ball hits a wall at 12 m/s and bounces straight back at 10 m/s. The contact lasts 50 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.2 kgvin = 12 m/svout = 10 m/sΔt = 50 ms
J = N·s
6.Hard
A 1000 kg car runs into a parked 1100 kg car. The wrecks lock together and skid 8 m before stopping. The coefficient of kinetic friction between tyres and road is 0.7. Use g = 9.81 m/s². Find the speed v1 of the first car just before the collision.
m1 = 1000 kgm2 = 1100 kgd = 8 mμ = 0.7g = 9.81 m/s²
v1 = m/s
Answer key
- 1. V = 1.35 m/s
- 2. v′ = 3 m/s
- 3. v′1 = 0.8889 m/s
- 4. v′2 = 5.714 m/s
- 5. J = 4.4 N·s
- 6. v1 = 22.01 m/s
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