Impulse and Impact

• What happens when a ball is hit?

Roger Federer backhands a tennis ball.
It doesn't look like he's working hard, does it?
Check out the shape of the ball.

This is a famous photo by Harold "Doc" Edgerton.
Notice the shape of the ball.  The degree of deformation
shown here is actually small compared to what happens
when a major league batter slams a fastball for a home run.

Notice how the golf ball changes shape over time.
The deformation is greatest in the center picture
when the force on the ball is greatest.
The force on the ball increases to a maximum and then
decreases to zero as the ball leaves the club.