Pocket Genius Science: Energy and forces – What is energy?

Facts At Your Fingertips: Energy and forces – What is energy?

Energy is what makes everything happen. It cannot be created or destroyed, but it can be transferred. For example, kicking a ball transfers energy from the person to the ball.

Energy can also be converted from one form to another—as when the chemical energy in gasoline is converted into the kinetic energy in a moving car.

Kinetic energy

The energy an object has because it is moving is called kinetic energy. A ball thrown into the air or a roller coaster hurtling down a track both have kinetic energy.

The greater the mass of an object and the faster it moves, the more kinetic energy it will have.

Chemical energy

Energy stored in substances is called chemical energy, and it can only be released through a chemical reaction. Chemical energy is stored in food, which must be broken down and its energy released by the body’s metabolism.

Potential energy

An object can store energy and release it later. Stored energy is also called potential energy because it has the potential to make things happen.

A coiled spring has potential energy, as does an archer’s bow when it is drawn and ready to shoot an arrow. When the spring is not coiled and the bow not drawn, they have no potential energy.

Energy chain

Energy can take many different forms, from the heat of the Sun to the chemical energy stored in sugar.

This energy chain shows how energy can be converted from one form to another.

Energy resources

Humans harness energy from many sources to supply power to their homes and vehicles. These include solar power, wind power, and nuclear power.

The vast majority of our power, however, comes from fossil fuels, such as oil, coal, and gas.

Saving energy

One day the supply of fossil fuels will run out and we may face energy shortages. It is important to save energy, for example, by using low-energy light bulbs and insulating homes.

Many governments have also begun investing in reusable sources of energy, such as solar and wind power.

When humans eat the fruits, the chemical energy is transferred to their bodies and used for all kinds of things. Winding up an alarm clock, for example, changes this chemical energy to potential energy in the spring of the alarm.

The potential energy of the wound-up spring is converted into the kinetic energy of the alarm bell and the sound energy of the alarm. The clock keeps working until the spring is unwound and has lost its potential energy.