Energy Transformations

• Several forms of energy have been defined.

• Each kind can be changed into other kinds

Chemical Energy• energy stored in bonds that hold atoms

together as molecules.

Food

Fuel

Nuclear Energy• energy stored in the nucleus of an atom;

released when nuclei split apart or join together

Nuclear FissionNuclear Fusion

Nuclear Power Plants Fusion in the sun

Gravitational Energy

• energy stored in an object as the result of its height

Roller coaster car at top of hill

Pendulum

Elastic Potential Energy• energy stored in elastic materials as the result

of their stretching or compressing.

Stretched Rubber Band

Compressed spring

Electrical Energy

Lightning

Energy of moving electrical charges

Electrical charges moving through wire

Radiant Energy

• Energy that travels as electromagnetic waves.

Xrays

Microwaves

“David Banner belted by gamma rays turns into The Hulk”

Sound Energy

• Energy given off by vibrating objects; energy we can hear

Mechanical Energy

• Energy of motion used to do work

Flowing water

Wind

Your body when you move

Machines

Thermal Energy• Thermal energy is the energy an object has

due to the motion of its molecules. The faster the molecules in an object move, the more thermal energy the object has.

The lava flowing from this volcano has a large amountof thermal energy.

Forms of EnergyPotential: Stored Energy Kinetic: Energy of Motion

Chemical Energy Electrical Energy

Nuclear Energy Radiant Energy

Gravitational Energy Sound Energy

Stored Mechanical Energy Mechanical Energy

Thermal Energy

Energy can be changed, or transformed, from one form to another.

Energy Transformations

Mechanical Energy Electrical Energy

Mechanical energy of moving water can be transformed into electrical energy

A toaster transforms electrical energy into thermal energy to toast your bread

Electrical Energy

Thermal Energy

Your body transforms the chemical energy in your food to mechanical energy you need to move your muscles.

Chemical Energy

Mechanical Energy

Chemical energy in food is also transformed to the thermal energy your body uses to maintain temperature.

Chemical Energy Thermal Energy

Many common devices transform electrical energy into other forms. Thinks about the following devices in terms of energy transformations.

ceiling fan digital clock hair dryer

For each device, describe which form or forms of energy the electrical energy becomes.

Energy TransformationsYou Try It…

Electrical Mechanical

Electrical Radiant (Light)

Electrical ThermalElectrical Mechanical

Green plants change radiant energy (light) to chemical energy.

Radiant Energy Chemical Energy

Burning fuels changes chemical energy into mechanical energy

Chemical Energy Mechanical Energy

A lightbulb changes electrical energy to light energy

Electrical Energy Light Energy

In any energy transformation, some energy changes to heat.

Energy can be changed from one form to another but it can never be created or destroyed.

Conservation of Energy

A sliding hockey puck comes to rest because friction converts its kinetic energy into heat.

Energy and Friction

Einstein’s Theory of Relativity

Energy and Matter E = mc2

"It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing -- a somewhat unfamiliar conception for the average mind. Furthermore, the equation E is equal to m c-squared, in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa. The mass and energy were in fact equivalent, according to the formula mentioned above. This was demonstrated by Cockcroft and Walton in 1932, experimentally."

Videos on Relativity