Simple Machines

A Simple Machine is a machine with few or no moving parts. Simple machines make work easier.

A machine is a device used for multiplying forces or simply changing the direction of forces.

The six simple machines are:

Lever All levers have a rigid arm that turns on a fixed point called a fulcrum. Pushing down on one end of a lever results in the upward motion of the opposite end.

Pulley A pulley is like a lever where the point in the middle acts as a fulcrum. Pulling down on one end of a pulley can lift any object attached to the other end of the rope.

Wheel and Axle A wheel and axle is made of a lever (wheel) connected to a shaft (axle). When the axle is turned, the wheel moves at a greater distance than the axle, but less force is used to move it.

Inclined Plane An inclined plane redirects force to lift an object upward. The trade-off is that an object needs to be moved a longer distance than if it was lifted straight up but less force is needed.

Wedge A wedge turns a single downward force into two forces directed out to the sides. Wedges are used to split things.

Screw A screw is an inclined plane wrapped around a cylinder. A screw requires a small force acting over a long distance.

Compound Machines A device that combines one or more simple machines.

A machine eases the load either by changing the magnitude or direction of the force, but does not change the amount of work done. As you put work into a machine the machine does work on another object.

The force you exert on a machine is called the effort force. (Fe) The force exerted by a machine is called the resistance force. (Fr) The ratio of the resistance force to effort force is called Mechanical advantage.(MA)

MA = Fe _______ Fr