1.Easy
A 500 kg car moving at 14 m/s runs into a stationary 1300 kg car. The cars lock together. Find their common velocity v′ just after the collision (positive in the first car’s direction).
m1 = 500 kgv1 = 14 m/sm2 = 1300 kgv2 = 0 m/s
v′ = m/s
Momentum & collisions worksheet with answers
2.Easy
A 3 kg rifle, free to move, fires a 12 g bullet at 600 m/s. Both start at rest. Find the recoil speed V of the rifle.
M = 3 kgm = 12 gv = 600 m/s
V = m/s
3.Medium
A 9 kg projectile moving horizontally at 15 m/s explodes into two fragments that move along the same line. The 6 kg fragment continues forwards at 39 m/s. Find the velocity v′2 of the 3 kg fragment (positive in the original direction).
M = 9 kgu = 15 m/sm1 = 6 kgv′1 = 39 m/sm2 = 3 kg
v′2 = m/s
4.Medium
A 4.5 kg glider moving at 8 m/s makes a perfectly elastic head-on collision with a 2.5 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 = 4.5 kgm2 = 2.5 kgv1 = 8 m/sv2 = 0
v′1 = m/s
5.Hard
A 1500 kg car runs into a parked 900 kg car. The wrecks lock together and skid 5 m before stopping. The coefficient of kinetic friction between tyres and road is 0.75. Use g = 9.81 m/s². Find the speed v1 of the first car just before the collision.
m1 = 1500 kgm2 = 900 kgd = 5 mμ = 0.75g = 9.81 m/s²
v1 = m/s
6.Hard
A 0.25 kg ball hits a wall at 21 m/s and bounces straight back at 17 m/s. The contact lasts 40 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.25 kgvin = 21 m/svout = 17 m/sΔt = 40 ms
J = N·s
Answer key
- 1. v′ = 3.889 m/s
- 2. V = 2.4 m/s
- 3. v′2 = −33 m/s
- 4. v′1 = 2.286 m/s
- 5. v1 = 13.72 m/s
- 6. J = 9.5 N·s
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