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A. Simple machine—does work with only one movement; a machine made of a combination of simple machines is a compound machine.

B. Inclined plane—a flat, sloped surface

1. Less force is needed to move an object from one height to another using an inclined plane than is needed to lift the object.

2. As the inclined plane gets longer, the force needed to move the object gets smaller.

3. The mechanical advantage of an inclined plane is the length of the inclined plane divided by its height.

4. Inclined plane that moves—wedge; changes the direction of the applied force; example: your front teeth

5. Screw—Inclined plane wrapped around a cylinder or post; the screw threads form the inclined plane on a screw; the mechanical advantage of the screw is the length of the inclined plane wrapped around the screw divided by the length of the screw.

C. Lever—any rigid rod or plank that pivots about a point.

1. the point about which the lever pivots—fulcrum

2. Mechanical advantage—divide the distance from the fulcrum to the input force by the distance from the fulcrum to the output force.

3. Levers can be divided into classes depending on the position of the fulcrum.

D. Wheel and axle—two circular objects of different sizes that rotate together

1. The mechanical advantage of a wheel and axle is found by dividing the radius of the wheel by the radius of the axle.

2. In some cases, the input force turns the wheel, and the axle exerts the output force, resulting in a mechanical advantage greater than one; examples are a doorknob, a steering wheel, and a screwdriver.

3. In other cases, the input force turns the axle, and the wheel exerts the output force, resulting in a mechanical advantage of less than one; examples are a fan and a ferris wheel.

E. Pulley—grooved wheel with a rope or chain wrapped around it

1. Fixed pulleys, such as on window blinds or flagpoles, are attached to an overhead structure and change the direction of the force you exert; they have a mechanical advantage of one.

2.Moveable pulleys are attached to the object being lifted and allow you to exert a smaller force; they have a mechanical advantage of two.

3. Pulley system—combination of fixed and movable pulleys