Contrary to advice given him,a boy tries bowling on the ice.He releases his 7.3-kg bowling ball when he is sliding at 2.0 m/s,and the ball travels subsequently down the ice at 13 m/s.If,after releasing the ball,the boy is moving backward from his original direction of motion at 0.25 m/s,what is the boy's mass?
A)36 kg
B)50 kg
C)47 kg
D)64 kg

Question

Quizplus · Accepted Answer

The conservation of momentum principle applies here. Initially, the momentum of the system (boy plus ball) is the sum of their individual momenta. After releasing the ball, the total momentum must remain the same. Let $m_b$ be the mass of the boy. The initial momentum is $m_b \times 2.0 + 7.3 \times 2.0$. After releasing the ball, the momentum is $7.3 \times 13 + m_b \times (-0.25)$ (negative because the boy moves backward). Setting these equal and solving for $m_b$ gives the boy's mass as 36 kg.

Contrary to Advice Given Him,a Boy Tries Bowling on the Ice.He