A force is a push or a pull. Force gives an object the energy to move, stop moving, or change direction. When you write with a pen you exert a force. When you peddle your bike, blow your nose, turn on a faucet, chew your gum, or swimming in a pool, you are exerting forces on other objects. We would never be able to move without exerting forces on things. Other examples are:

*	A flag being blown by the force of the wind.
*	Iron being pulled towards a magnet.
*	A jet engine propelling an airplane forward.

For practice list five examples of a force moving an object.
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Friction is a force that opposes motion. Friction acts in a direction opposite to the object's direction in motion. Without friction, the object would continue to move at a constant speed forever. There are different forms of friction.

One type is called sliding friction. This is when two surfaces slide one over the other. A snowboarder slides over the snow covered slopes using sliding friction everyday.

When an object rolls over a surface, the kind of friction that occurs is rolling friction. Skate boarders take advantage of this type of friction all the time. Reducing the amount of friction between the surface and the wheels allow skaters to go really fast.

Friction also occurs in fluids (gases and liquids). This is how a surfer glides over the water or a shark glides through the water. This type is called fluid friction.

For practice list five examples of friction.
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