Question

Playing in the street, a child accidentally tosses a ball at 25 m/s toward the front of a car moving toward him at 13 m/s . Part A What is the ball's speed after it rebounds elastically from the car? Express your answer in meters per second.

Answer 1

The ball's speed after it rebounds elastically from the car is 1 m/s.

How to calculate the speed of the ball?

The speed of the ball is calculated by applying the principle of conservation of linear momentum as follows;

Sum of initial momentum = sum of final momentum

We will also consider one direction velocity formula;

v₁ + u₁ = v₂ + u₂

where;

• u₁ is the initial velocity of the car
• v₁ is the final velocity of the car
• u₂ is the initial velocity of the ball
• v₂ is the final velocity of the ball

Since the mass of the car will be so large compared to the ball, the change in the speed of the car will be insignificant.

13 + 13 = 25 + v₂

26 = 25 + v₂

v₂ = 26 - 25

v₂ = 1 m/s

So the final velocity of the ball is 1 m/s.