1.Easy
A 6 kg rifle, free to move, fires a 10 g bullet at 700 m/s. Both start at rest. Find the recoil speed V of the rifle.
M = 6 kgm = 10 gv = 700 m/s
V = m/s
Momentum & collisions worksheet with answers
2.Easy
A 1400 kg car moving at 6 m/s runs into a stationary 1100 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 = 6 m/sm2 = 1100 kgv2 = 0 m/s
v′ = m/s
3.Medium
A 5 kg glider moving at 11 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 = 5 kgm2 = 2.5 kgv1 = 11 m/sv2 = 0
v′1 = m/s
4.Medium
A 3 kg glider moving at 12 m/s makes a perfectly elastic head-on collision with a 4 kg glider at rest on a frictionless track. Find the velocity v′2 of the second glider after the collision.
m1 = 3 kgm2 = 4 kgv1 = 12 m/sv2 = 0
v′2 = m/s
5.Hard
A 0.1 kg ball hits a wall at 11 m/s and bounces straight back at 9 m/s. The contact lasts 50 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.1 kgvin = 11 m/svout = 9 m/sΔt = 50 ms
J = N·s
6.Hard
An 8 g bullet is fired horizontally into a 3 kg block hanging from light strings 0.8 m long, and stays in it. The strings swing out to a largest angle of 20° from the vertical. Use g = 9.81 m/s². Find the speed v of the bullet before impact.
m = 8 gM = 3 kgL = 0.8 mθ = 20°g = 9.81 m/s²
v = m/s
Answer key
- 1. V = 1.167 m/s
- 2. v′ = 3.36 m/s
- 3. v′1 = 3.667 m/s
- 4. v′2 = 10.29 m/s
- 5. J = 2 N·s
- 6. v = 365.8 m/s
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