1.Easy
A 1600 kg car moving at 11 m/s runs into a stationary 600 kg car. The cars lock together. Find their common velocity v′ just after the collision (positive in the first car’s direction).
m1 = 1600 kgv1 = 11 m/sm2 = 600 kgv2 = 0 m/s
v′ = m/s
Momentum & collisions worksheet with answers
2.Easy
A 2000 kg car moving at 14 m/s collides head-on with a 1300 kg car moving at 8 m/s in the opposite direction. The cars lock together. Find their common velocity v′ just after the collision (positive in the first car’s direction).
m1 = 2000 kgv1 = 14 m/sm2 = 1300 kgv2 = −8 m/s
v′ = m/s
3.Medium
A 15 g bullet is fired horizontally into a 4 kg wooden block hanging on light strings, and stays inside it. The block swings up until it is 6 cm higher than at the start. Use g = 9.81 m/s². Find the speed v of the bullet before impact.
m = 15 gM = 4 kgh = 6 cmg = 9.81 m/s²
v = m/s
4.Medium
A 1700 kg car moving at 7 m/s runs into a stationary 1700 kg car and the two lock together. What percentage ΔK/K of the original kinetic energy is lost?
m1 = 1700 kgv1 = 7 m/sm2 = 1700 kgv2 = 0
ΔK/K = %
5.Hard
A 900 kg car runs into a parked 1600 kg car. The wrecks lock together and skid 14 m before stopping. The coefficient of kinetic friction between tyres and road is 0.7. Use g = 9.81 m/s². Find the speed v1 of the first car just before the collision.
m1 = 900 kgm2 = 1600 kgd = 14 mμ = 0.7g = 9.81 m/s²
v1 = m/s
6.Hard
A 0.1 kg ball hits a wall at 12 m/s and bounces straight back at 17 m/s. The contact lasts 20 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.1 kgvin = 12 m/svout = 17 m/sΔt = 20 ms
J = N·s
Answer key
- 1. v′ = 8 m/s
- 2. v′ = 5.333 m/s
- 3. v = 290.4 m/s
- 4. ΔK/K = 50 %
- 5. v1 = 38.52 m/s
- 6. J = 2.9 N·s
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