In this topic you will learn about how energy is used to do work.

Some actions are work. Other actions are not work. Scientists say that work is done when a force moves an object. Picking up books or shaking a rattle are examples of work. A pulling force from the hands moves the book up. The shaking force of the arm moves the rattle back and forth. Pushing against a wall is not work because there is no motion. The wall does not move.

To do work you need energy. Energy is the ability to do work. Energy exists in different forms. Moving things, like a rock rolling down a hill, have energy of motion.

Sometimes objects have the ability to move because of their position. A rock that is on top of a hill is in a position to move. Energy that can cause an object to move is called stored energy. Other forms of energy include heat, light, sound, and electricity. Energy moves from place to place, and changes from one form to another. If a wood block is rubbed with sandpaper, the block will feel warmer. The energy of the moving sandpaper is changed to heat energy.

When people talk about work, they usually mean a job that adults do. Whether you have a job or not, you work every day. You work when you pedal a bike. You work when you jump rope. You even work a little bit when you do your homework.