The Secret Lives of Eenrgy - The Energy Story

The Energy Story

	Exercise 1
	Exercise 2
	The Ten Types

	- Kinetic
	- Gravitational
	- Spring
	- Electrical
	- Magnetic
	- Mechanical
	- Heat
	- Nuclear
	- Light
	- Chemical

	Crossword
	Energy Game

Energy Changes

Energy Generation

The Energy Problem

The Energy Solution

Secret Lives Title - The Energy Story

The Ten Types
Gravitational Energy

Gravitational energy is due to the force of gravity caused by the attraction of all other masses to the mass of the earth. As you lift an object to a higher elevation, you give that object increased gravitational energy. You can get that energy back (or most of it) when you drop the object and it falls to the earth's surface.

The amount of gravitational energy that an object possesses can be calculated from the equation:

where	GPE = gravitational potential energy m = mass g = acceleration of gravity h = height above the ground (or a reference level)
The acceleration of gravity near the surface of the earth is constant, around 9.8 meters per second squared. Therefore the GPE is directly proportional to the mass and directly proportional to the height.

An example of a device that uses GPE is the pile driver. A huge cylinder of metal is raised and then dropped on wooden piles to drive them into the ground. Then there is the device that drops a metal object onto soda cans to flatten them so they are easier to store before disposal.

The most common use of GPE is in hydroelectric power plants that use the GPE of water to generate electricity. Nature conveniently evaporates water which then rains on ground that is at a higher elevation. The water therefore possesses more GPE which can be released when the water is allowed to fall over a dam.