Types of EnergyForms of Energy

Law of Conservation of Energy

Work

Renewable and Nonrenewable Sources

Radiant ElectricalChemical

Thermal Nuclear

Magnetic

Sound

Mechanical

Renewable Nonrenewable

Kinetic Energy Potential Energy

Potential energy + Kinetic energy = Mechanical energy

Example of energy changes in a swing or pendulum.

The greater the mass or velocity of a moving object, the more kinetic energy it has.

Kinetic energy exists whenever an object which has mass is in motion with some velocity. Everything you see moving about has kinetic energy.  The kinetic energy of an object in this case is given by the relation:

KE = (1/2)mv2

m=mass of the object

V=velocity of the object

The greater the mass or velocity of a moving object, the more kinetic energy it has.

Potential energy exists whenever an object which has mass has a position within a force field. The most everyday example of this is the position of objects in the earth's gravitational field. The potential energy of an object in this case is given by the relation:

PE = mgh

 PE = Energy (in Joules)

m = mass (in kilograms)

g = gravitational acceleration of the earth (9.8 m/sec2)

h = height above earth's surface (in meters)

Law of Conservation of Energy- Energy can neither be created nor destroyed. Energy is always changing from one kind to another. The total energy of an object never changes.

Potential energy + Kinetic energy = Total energy and

Total energy – Kinetic energy = Potential energy and

Total energy - Potential energy = Kinetic energy

Work is the transfer of energy through motion. In order for work to take place, a force must be exerted through a distance. The amount of work done depends on two things: the amount of force exerted and the distance over which the force is applied. There are two factors to keep in mind when deciding when work is being done: something has to move and the motion must be in the direction of the applied force. Work can be calculated by using the following formula:

Work = force x distance

Work = KE

W = F d cosat anangle)

Check Your Understanding

A = 50 J D = 50 J G = 100 J J = 100

B = 7m/s E = 7 m/s H = 10 m/s K = 10 m/s

C = 50 J F = 0 J I = 0 J

Check Your Understanding

• 1) How much work is required to lift a 162 kilogram piano to a window whose height is 4.5 meters from the ground?

W = F x distance

F = 162Kg x 9.8m/s2 = 1590 N

W = 1590 N x 4.5 m = 7200 Nm