Two ice skaters, Daniel (mass 65.0 $\mathrm{kg} )$ and Rebecca (mass $45.0 \mathrm{kg} ),$ are practicing. Daniel stops to tie his shoelace and, while at rest, is struck by Rebecca, who is moving at 13.0 $\mathrm{m} / \mathrm{s}$ before she collides with him. After the collision, Rebecca has a
velocity of magnitude 8.00 $\mathrm{m} / \mathrm{s}$ at an angle of $53.1^{\circ}$ from her initial direction. Both skaters move on the frictionless, horizontal surface of the rink. (a) What are the magnitude and direction of Daniel's velocity after the collision? (b) What is the change in total kinetic energy of the two skaters as a result of the collision?