# A 90 kg man is standing still on frictionless ice. His friend tosses him a 10 kg ball, which has a horizontal velocity of 20 m/s. After catching the ball, what is the man's velocity?

Jan 15, 2016

2 $\frac{m}{s}$

#### Explanation:

Using Law of Conservation of momentum.
Initial momentum is equal to final momentum
Momentum = ${M}_{m a n} . {v}_{m a n} + {m}_{b a l l} . {v}_{b a l l}$

Initial momentum = $90 \times 0 + 10 \times 20$

After the man catches the ball both ball and man move with the same velocity. Therefore
Final Momentum = $\left({M}_{m a n} + {m}_{b a l l}\right) . {v}_{f i n a l}$
Equating the two

$200 = 100 \times {v}_{f i n a l}$