**A 100.0-kg athlete is running at 10.0 m/s. At what speed would a 0.10-kg ball need to travel in the same direction so that the momentum of the athlete and the momentum of the ball would be equal?**

**Answer:**

Momentum=mass∗velocity

Since we want the momentum of the ball to be equal to that of the athlete.

M (athlete) = mass of athlete * velocity of athlete

M (athlete) = 100kg * 10m/s

M (athlete) = 1000 kg m/s = 1000 N/s

Let the velocity of the ball be v.

M (ball) = mass of ball * velocity of ball

M (ball) = 0.10kg * v m/s

M (ball) = 0.10v kg m/s = 0.10v N/s

Since, M (athlete) = M (ball)

So, 1000 N/s = 0.10v N/s

Hence, v = 10000 m/s

So, the speed of the ball needs to be 10000 m/s, so that it may have its momentum equal to that of the athlete.