## College Physics (4th Edition)

The speed of the raft is $0.50~m/s$ in the opposite direction from the person's motion.
We can assume the initial momentum of the person and the raft is zero. By conservation of momentum, if the person gains a certain momentum $p_p$ in one direction, the raft will gain the same magnitude of momentum $p_r$ in the opposite direction. We can find the speed $v_r$ of the raft: $p_r = p_p$ $m_r~v_r = m_p~v_p$ $v_r = \frac{m_p~v_p}{m_r}$ $v_r = \frac{(55~kg)(0.91~m/s)}{100.0~kg}$ $v_r = 0.50~m/s$ The speed of the raft is $0.50~m/s$ in the opposite direction from the person's motion.