“On your marks!
These are the orders the starter shouts when you take part in a running race.
When you are running, your body has a lot of kinetic energy, the energy of movement. When you are “on your marks,” you use a small amount of energy. Most of your energy is stored, or saved up, ready for the running of the race.
Energy that is stored and waiting to be used is called potential energy.
Potential energy is often linked to work that has already been done. Take a ball and place it on the floor. Now put the ball on a high shelf. The ball has more potential energy when it is on the shelf than it has on the floor. The ball has gained this extra energy because work was done when the ball was placed on the high shelf. Do you know how to turn the potential, or stored, energy of the ball into kinetic, or moving, energy?
How is energy stored?
An archer’s bow has potential energy when it is bent. When the archer releases the bow, this potential energy changes into kinetic energy, and the arrow shoots forwards. When you wind up a clock, potential energy is stored in the clock’s spring. This energy changes into the kinetic energy that makes the clock work.
The potential energy of this archer’s bent bow will turn into kinetic energy when the archer releases the bow’s string.