A 45.0 kg ice skater stands at rest on the ice. A friend tosses the skater a 5.0 kg ball. The skater and the ball then move backwards across the ice with a speed of 0.5 m/s. What was the speed of the ball at the moment just before the skater caught it?

u = 5 m/s

Explanation:

given,

Mass of ice skater, M = 45 Kg

initial speed = 0 m/s

mass of the ball, m = 5 Kg

velocity of skater and the ball, V = 0.5 m/s

speed of the ball = ?

using conservation of momentum

m u + M u' = (M + m) V

initial speed of ice skater is zero

5 x u + 45 x 0 = (45 + 5) V

5 u = 50 x 0.5

5 u = 25

u = 5 m/s

hence, the speed of the ball is equal to 5 m/s