Acar moving with an initial speed v collides with a second stationary car that is one-half as massive. after the collision the first car moves in the same direction as before with a speed v/3. find the final speed of the second car.

4v/3

Explanation:

Assume elastic collision by the law of momentum conservation:

where v is the original speed of car 1, v1 is the final speed of car 1 and v2 is final speed of car 2. m1 and m2 are masses of car 1 and car 2, respectively

Substitute

Divide both side by , then multiply by 6 we have

So the final speed of the second car is 4/3 of the first car original speed