Energy in a
Imagine throwing a ball against a wall
as hard as you can. What will happen when it hits the
Bounces Off Wall
Everyone knows that it will
Anything in motion has
kinetic energy---energy of motion. The kinetic
energy of the moving ball is converted to potential
energy as the ball is squashed into the wall. This
potential energy becomes kinetic energy again as
the ball springs back into shape and propels itself
away from the wall.
The change in the direction of the
ball is caused by the elastic nature of the ball itself.
Much like a spring, the ball "squashed" itself against the
wall then rebounds as it becomes round again.
Now imagine that the wall is moving
and has its own kinetic energy. At the moment of collision,
the wall transfers some of that energy to the
Remember the energy that the ball has when you throw it
against a wall? It has the same energy when it hits a bat.
But a swinging bat adds energy too. The combined energies
make hitting a home run easier when a baseball is
Now think about hitting a
baseball from a tee. All of the energy in this
system starts with the batter and is transferred to
the bat. Some of the energy in the bat is then
transferred to the ball causing it to fly off the
Hitting a baseball that is
pitched involves more total energy. The ball has
energy and the bat has energy.
Why are most home runs hit off of
© 2003-2005 Event-Based Science Project