1.Easy
A 1500 kg car moving at 16 m/s runs into a stationary 800 kg car. The cars lock together. Find their common velocity v′ just after the collision (positive in the first car’s direction).
m1 = 1500 kgv1 = 16 m/sm2 = 800 kgv2 = 0 m/s
v′ = m/s
Momentum & collisions worksheet with answers
2.Easy
A 0.25 kg ball at rest is kicked. The foot pushes it with an average force of 650 N for 5 ms. Find the speed v of the ball just after the kick.
m = 0.25 kgFavg = 650 NΔt = 5 ms
v = m/s
3.Medium
A 4 kg glider moving at 8 m/s makes a perfectly elastic head-on collision with a 4.5 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 kgm2 = 4.5 kgv1 = 8 m/sv2 = 0
v′1 = m/s
4.Medium
An 11 kg projectile moving horizontally at 37 m/s explodes into two fragments that move along the same line. The 10 kg fragment continues forwards at 49 m/s. Find the velocity v′2 of the 1 kg fragment (positive in the original direction).
M = 11 kgu = 37 m/sm1 = 10 kgv′1 = 49 m/sm2 = 1 kg
v′2 = m/s
5.Hard
A 0.55 kg ball hits a wall at 27 m/s and bounces straight back at 16 m/s. The contact lasts 50 ms. Find the magnitude of the impulse J the wall gives the ball.
m = 0.55 kgvin = 27 m/svout = 16 m/sΔt = 50 ms
J = N·s
6.Hard
A 1500 kg car runs into a parked 1200 kg car. The wrecks lock together and skid 21.5 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 = 1500 kgm2 = 1200 kgd = 21.5 mμ = 0.7g = 9.81 m/s²
v1 = m/s
Answer key
- 1. v′ = 10.43 m/s
- 2. v = 13 m/s
- 3. v′1 = −0.4706 m/s
- 4. v′2 = −83 m/s
- 5. J = 23.65 N·s
- 6. v1 = 30.93 m/s
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