1.Easy
A 4.5 kg rifle, free to move, fires an 8 g bullet at 400 m/s. Both start at rest. Find the recoil speed V of the rifle.
M = 4.5 kgm = 8 gv = 400 m/s
V = m/s
Momentum & collisions worksheet with answers
2.Easy
A 3.5 kg rifle, free to move, fires a 10 g bullet at 550 m/s. Both start at rest. Find the recoil speed V of the rifle.
M = 3.5 kgm = 10 gv = 550 m/s
V = m/s
3.Medium
A 17 kg projectile moving horizontally at 37 m/s explodes into two fragments that move along the same line. The 11 kg fragment continues forwards at 82 m/s. Find the velocity v′2 of the 6 kg fragment (positive in the original direction).
M = 17 kgu = 37 m/sm1 = 11 kgv′1 = 82 m/sm2 = 6 kg
v′2 = m/s
4.Medium
A 2 kg glider moving at 9 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 = 2 kgm2 = 1.5 kgv1 = 9 m/sv2 = 0
v′2 = m/s
5.Hard
A 0.15 kg ball hits a wall at 18 m/s and bounces straight back at 11 m/s. The contact lasts 10 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.15 kgvin = 18 m/svout = 11 m/sΔt = 10 ms
J = N·s
6.Hard
A 1700 kg car runs into a parked 1700 kg car. The wrecks lock together and skid 11.5 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 = 1700 kgm2 = 1700 kgd = 11.5 mμ = 0.5g = 9.81 m/s²
v1 = m/s
Answer key
- 1. V = 0.7111 m/s
- 2. V = 1.571 m/s
- 3. v′2 = −45.5 m/s
- 4. v′2 = 10.29 m/s
- 5. J = 4.35 N·s
- 6. v1 = 21.24 m/s
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