A 0.5-kg baseball is pitched at 45 m/s and is struck by a bat and sent back toward the pitcher at -45 m/s. If the ball is in contact with the bat for 0.0025 seconds, how hard does the bat hit the ball? What forces act on the ball after the bat hits it?

To determine how hard the bat hits the ball, we need to calculate the impulse experienced by the ball during the bat-ball collision. Impulse is a measure of how a force affects an object over a specific period of time and can be calculated using the formula:

Impulse = Force * Time

In this case, we have the mass of the ball (0.5 kg), the initial velocity of the ball (v1 = 45 m/s), the final velocity of the ball (v2 = -45 m/s), and the time the ball is in contact with the bat (0.0025 seconds).

To find the force exerted by the bat on the ball, we rearrange the formula:

Force = Impulse / Time

First, let's calculate the impulse:

Impulse = (final momentum - initial momentum)

Momentum is calculated using the formula:

Momentum = Mass * Velocity

The initial momentum of the ball is:

Initial momentum = Mass * initial velocity
= 0.5 kg * 45 m/s

The final momentum of the ball is:

Final momentum = Mass * final velocity
= 0.5 kg * (-45 m/s)

Now, we can calculate the impulse:

Impulse = (Final momentum - Initial momentum)
= (0.5 kg * (-45 m/s)) - (0.5 kg * 45 m/s)

Next, we calculate the force:

Force = Impulse / Time

Finally, we can substitute the values into the formula to find the force exerted by the bat on the ball.

Regarding the forces acting on the ball after the bat hits it, several forces come into play, including gravitational force, air resistance, and the force of friction with the air. These forces will affect the ball as it moves through the air and slows down due to its speed and these opposing forces. However, for a more detailed analysis of the forces acting on the ball, additional factors such as spin, elevation, and weather conditions might need to be considered.