With what magnitude of force does a ball of mass 0.75 kilograms need to be hit so that it accelerates at the rate of 25 meters/second2? Assume that the ball undergoes motion along a straight line

Force = (mass) x (acceleration)

= (0.75 kg) x (25 m/s²)

= (0.75 x 25) kg-m/s²

= 18.75 newtons.

Note that even though we're talking about a 'hit', the acceleration only

lasts as long as the bat is in contact with the ball. Once the ball leaves

the bat, it travels at whatever speed it had at the instant when they parted.

Any change in its speed or direction after that is the result of gravity, air

resistance, and the fielder's mitt. I learned a lot about these things a few

weeks ago, since I live in Chicago, about 6 miles from Wrigley Field, in

a house full of Cubs fans.