Simple Machines  Simple machines are basic machines that are the basis for all other forms of machines.  There are six types of simple machines:  1. Simple Lever  2. Pulley  3. Wheel and Axle  4. Inclined Plane  5. Wedge  6. Screw

Simple Machines  Simple machines are divided into 2 families  Lever Family Simple Lever Pulley Wheel and Axle  Inclined Plane Family Simple Inclined Plane Wedge Screw

The Lever Family  All levers have a rigid arm that turns around a point called the fulcrum.  Levers are divided into three classes depending on the location of the fulcrum, input force, and output force.

First Class Levers  The fulcrum is located between the points of application of the input and output forces.  Example- Claw Hammer

Second Class Levers  The fulcrum is at one end of the arm, and the input force is applied at the other end.  Example- Wheelbarrow

Third Class Levers  The fulcrum is located at one end of the arm, and the output is found at the other end.  Example- Biceps

Pulleys  Pulleys are levers. The middle of the pulley is the fulcrum. The rest of the pulley acts like a first class lever.

Wheel and Axle  The steering wheel of a car is a lever. It’s made of a pulley (wheel) attached to a shaft (axle).

Inclined Plane Family  Pushing an object up an inclined plane requires less input force than lifting the same object does.  Pushing an object up a long gradual ramp requires less force than pushing up a short steep ramp.

Wedge  A wedge turns a downward force into two forces directed out to the sides.  An ax blade or a wedge pushes through and breaks apart the wood.

Screw  A screw is an inclined plane wrapped around a cylinder.  Tightening a screw with threads requires small force to act over a long distance.

Compound Machines  A machine that uses more than one simple machine.  A pair of scissors uses 2 first class levers joined at a fulcrum. Each arm has a wedge that cuts the paper.