1.Easy
A 3 kg rifle, free to move, fires a 15 g bullet at 350 m/s. Both start at rest. Find the recoil speed V of the rifle.
M = 3 kgm = 15 gv = 350 m/s
V = m/s
Momentum & collisions worksheet with answers
2.Easy
A 900 kg car moving at 7 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 = 900 kgv1 = 7 m/sm2 = 1300 kgv2 = 0 m/s
v′ = m/s
3.Medium
A 0.5 kg glider moving at 5 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 = 0.5 kgm2 = 4 kgv1 = 5 m/sv2 = 0
v′2 = m/s
4.Medium
An 18 kg projectile moving horizontally at 20 m/s explodes into two fragments that move along the same line. The 16 kg fragment continues forwards at 59 m/s. Find the velocity v′2 of the 2 kg fragment (positive in the original direction).
M = 18 kgu = 20 m/sm1 = 16 kgv′1 = 59 m/sm2 = 2 kg
v′2 = m/s
5.Hard
A 0.55 kg ball hits a wall at 20 m/s and bounces straight back at 9 m/s. The contact lasts 40 ms. Find the average force Favg of the wall on the ball.
m = 0.55 kgvin = 20 m/svout = 9 m/sΔt = 40 ms
Favg = N
6.Hard
A 0.55 kg ball hits a wall at 21 m/s and bounces straight back at 14 m/s. The contact lasts 40 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.55 kgvin = 21 m/svout = 14 m/sΔt = 40 ms
J = N·s
Answer key
- 1. V = 1.75 m/s
- 2. v′ = 2.864 m/s
- 3. v′2 = 1.111 m/s
- 4. v′2 = −292 m/s
- 5. Favg = 398.8 N
- 6. J = 19.25 N·s
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