Question

A 125kg bumper car going 18.5 m/a bumps a 187.kkg bumper car at rest. if the first car (125kg) bounces back at 8 m/s what is the velocity of the 2nd car after the collision

Answer 1

  Imagine we have a 2 lb ball of putty moving with a speed of 5 mph striking and sticking to a 18 lb bowling ball at rest; the time it takes to collide is 0.1 s. After the collision, the two move together with a speed of v1. To find v1, use momentum conservation: 2x5=(18+2)v1, v1=0.5 mph. Next, imagine we have a 18 lb bowling ball moving with a speed of 5 mph striking and sticking to a 2 lb ball of putty at rest; the time it takes to collide is 0.1 s. After the collision, the two move together with a speed of v2. To find v2, use momentum conservation: 18x5=(18+2)v2, v2=4.5 mph. 

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