Part $($a$)$

Write an expression for the ball's velocity, v$,$ in terms of the variables m$,$ t$,$ and F$,$ just after it rebounds from the floor. $($Hint: The fact that the collision is elastic is important when solving this problem.$)$

$$ Part $($b$)$

What is the magnitude of the ball's velocity v$,$ in meters per second, right after it rebounds?

v