THE SIX TYPES OF SIMPLE MACHINES

A simple machine increase the force applied to it. In other words, they produce an output force that is far greater than the input force. The ratio of the output force to the input force is referred to as the mechanical advantage.

Mechanical advantage =  Output force
                                               Input force

There are six simple machines. 

• Lever
• Wheel and Axle
• Wedge
• Inclined plane
• Screw
• Pulley

LEVER: A lever is a simple machine that consists of a rigid object (usually a bar) and a fulcrum (or pivot). Applying a force to one end of the rigid object causes it to pivot about the fulcrum, causing a magnification of the force at another point along the rigid object. The applied force is known as the effort; the output force is the load; the point where there is no movement is the pivot (fulcrum). There are three classes of levers based on the positions of 

the load, effort, and pivot.

First Class Machine: The pivot is between the effort and the load.
Second Class Machine: The load is between the effort and the pivot.

Third Class Machine: The effort is between the pivot and the load.

         CLASS (TYPE) OF LEVER          EXAMPLES         WHERE THE OCCUR IN HUMANS

WHEEL AND AXLE: A wheel is a circular device that is attached to a rigid bar in its center. A force applied to the wheel causes the axle to rotate and this can magnify the force.

Example is the Ferris Wheel.

INCLINED PLANE: An inclined plane is a plane surface set at an angle to another surface. This results in doing the same amount of work by applying the force over a longer distance.

Example is the ramp.

WEDGE: A wedge is a double-inclined plane (both sides are inclined) that moves to exert a force along the lengths of the sides. Examples: Axes, knives, and chisels.

SCREW: A screw is a shaft that has a in inclined groove along its surface. By rotating the screw, the force is applied perpendicular to the groove, thus translating a rotational force into a linear one. The rotational force is called a torque.

PULLEY: This is a wheel with a groove along its edge, where a rope or cable can be placed. It uses the principle that when force is applied over a longer distance it can reduce the magnitude of the necessary force need to perform some form of work.