Given that,
Mass of a baseball, m = 0.2 kg
Initial speed of a baseball, u = 30 m/s
Force produced by a bat, F = 2000 N
Final speed of a baseball, v = -50 (negative for opposite direction)
To find,
For how long was the ball in contact with the bat?
Solution,
Let for t seconds the ball is in contact with the bat. The net force acting on the ball is given by :

So, the ball is contact with the bat for 8 ms.