Answer to Question #261875 in Physics for Charlie

Question

A 30 g marble rolls with a velocity of 2 m/s toward a 70 g marble at rest. The lighter marble (m1) stops moving as its hits the heavier marble (m2). This collision causes the heavier marble to move. What is the velocity of the heavier marble?

Answer 1

We can find the velocity of the heavier marble after the collision from the law of conservation of momentum:

$$m_1v_{1i}+m_2v_{2i}=m_1v_{1f}+m_2v_{2f},$$ $$m_1v_{1i}=m_2v_{2f},$$ $$v_{2f}=\dfrac{m_1v_{1i}}{m_2}=\dfrac{0.03\ kg\times2\ \dfrac{m}{s}}{0.07\ kg}=0.86\ \dfrac{m}{s}.$$