Chapter 15

Section 1

Energy and Its Forms

Work and energy are closely related. When work is done on an object, energy is

transferred to that object.

Many forms of energy can be classified into two general types: kinetic energy

and potential energy.

•The sun gives off energy in the forms of heat and light.•Plants convert sunlight into

food than we can eat.•People convert food energy

into muscle movement.

The kinetic energy of any moving object depends upon its mass and speed.

Kinetic Energy

Potential Energy that depends upon an object’s height is called gravitational potential energy. It increases when an object is raised to a higher level.

Energy of each type can be converted into other forms of energy.

Further Examples and Explanation of Energy

• Mechanical energy - the sum (total) of an object’s potential energy and kinetic energy.

• Thermal energy - really a measure of how fast an object’s atoms are

moving.

• Chemical energy - when these bonds are broken, the released energy can do work.

• Electrical energy - Batteries convert chemical energy to electrical energy. Lightning is electrical energy.

• Electromagnetic energy - a form of energy that travels through space in the form of waves. Because they can travel long distances through air and space, they are often used for communication.

• Nuclear energy - Nuclear power plants use fission – splitting the nuclei of atoms apart to release energy. The sun uses fusion – two hydrogen nuclei combine the larger helium nuclei. (A tiny amount of mass is lost in the process – which produces huge amounts of energy.)