If the collision between the baseball and the bat lasted 1.00 ms (milliseconds), what force did the bat exert on the baseball?

According to Newton's second law of motion, the force can be calculated as the rate of change of momentum. That is,

force = rate of change of momentum

= (final momentum - initial momentum) / time interval

The momentum can be calculated as the product of mass and velocity.

Since the mass of the object stays constant, the force can be calculated as:

force = m (final velocity - initial velocity) /  time interval

where m is the mass of the object.

In this question, the mass of the baseball and its velocity before and after hitting the bat are not given. Without them, we cannot solve for the force. Only the time interval is given as 1 ms.

Assuming that the mass of the baseball is 100 g (= 0.1 kg) and it was traveling at say, 20 m/s and after contact with the bat, it started moving at 50 m/s. In that case, the force applied can be calculated as:

force = 0.1 kg x (50 - (-20)) m/s / 0.001 s = 7 x 10^3 N or 7 kN.

Hope this helps.