1.Easy
An 800 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 = 800 kgv1 = 13 m/sm2 = 2000 kgv2 = 0 m/s
v′ = m/s
Momentum & collisions worksheet with answers
2.Easy
A 4 kg rifle, free to move, fires an 8 g bullet at 800 m/s. Both start at rest. Find the recoil speed V of the rifle.
M = 4 kgm = 8 gv = 800 m/s
V = m/s
3.Medium
A 0.5 kg glider moving at 7 m/s makes a perfectly elastic head-on collision with a 1.5 kg glider at rest on a frictionless track. Find the velocity v′2 of the second glider after the collision.
m1 = 0.5 kgm2 = 1.5 kgv1 = 7 m/sv2 = 0
v′2 = m/s
4.Medium
A 2 kg glider moving at 11 m/s makes a perfectly elastic head-on collision with a 3.5 kg glider at rest on a frictionless track. Find the velocity v′2 of the second glider after the collision.
m1 = 2 kgm2 = 3.5 kgv1 = 11 m/sv2 = 0
v′2 = m/s
5.Hard
A 900 kg car runs into a parked 800 kg car. The wrecks lock together and skid 17 m before stopping. The coefficient of kinetic friction between tyres and road is 0.5. Use g = 9.81 m/s². Find the speed v1 of the first car just before the collision.
m1 = 900 kgm2 = 800 kgd = 17 mμ = 0.5g = 9.81 m/s²
v1 = m/s
6.Hard
A 0.2 kg ball hits a wall at 28 m/s and bounces straight back at 20 m/s. The contact lasts 10 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.2 kgvin = 28 m/svout = 20 m/sΔt = 10 ms
J = N·s
Answer key
- 1. v′ = 3.714 m/s
- 2. V = 1.6 m/s
- 3. v′2 = 3.5 m/s
- 4. v′2 = 8 m/s
- 5. v1 = 24.39 m/s
- 6. J = 9.6 N·s
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