Energy and Power The Nature of Energy

What is energy? The ability to work or cause change is called energy. When an object or organism does work on another object,

some of its energy is transferred to that object. Think of work as the transfer of energy. Work = Force x Distance There are 2 types of energy: Kinetic and Potential

What is a joule?

The amount of work you do when you exert a force of 1 newton to move an object a distance of 1 meter.

Weight is measured in newtons and Height is measured in meters, the unit of energy is the newton-meter.

Kinetic Energy

The energy of motion is called kinetic energy. Kinetic: Greek word kinetos =“Moving” Kinetic energy of an object depends on both its

mass and its velocity. Kinetic energy increase as mass increases.

(golf and bowling ball) Kinetic energy increases as mass and velocity

increase.

Calculating Kinetic Energy

Changing the velocity of an object will have a greater effect on its kinetic energy than changing its mass.

Kinetic energy = Mass x Velocity2

2

Potential Energy Energy that is stored and held in readiness. An archer gives potential energy to a bow by pulling it back. A rock poised for fall has potential energy.

Gravitational potential energy = Weight x Height

Different Forms of energy

Mechanical Energy: Is the energy associated with the motion or position of an object. (A Frog leaping through the air. The bus you ride in.) This form of energy can occur as kinetic or potential energy.

Thermal Energy: Total energy of the particles in a substance or material. (Melting ice, or ice-cream melting.)

Chemical Energy: Is potential energy stored in chemical bonds that hold chemical compounds together.

Forms of Energy Continued

Electrical Energy: Moving electric charges. (shock from a metal door, batteries or power lines.)

Electromagnetic Energy: Travels in waves. (Ultraviolet radiation, visible light, microwaves and infrared radiation)

Nuclear Energy: A potential energy that is stored in the nucleus of an atom and is releases during nuclear reactions.

Review of Energy

Are energy and work the same thing?

Work and energy are not the same thing, even though they are measured in the same units. Energy is the ability to do work. As work is done, energy is transferred from one object to another.

Review How are kinetic and potential energy

different? Kinetic energy is the energy of motion. Potential

energy is stored energy: it has the potential to do work.

Review List the forms of

energy and give an example.

Mechanical – riding a bicycle

Thermal – Hot water Chemical – food energy Electrical – batteries Electromagnetic –

sunlight Nuclear – fusion in a

star