Simple Machines make work easier for us by allowing us to push or pull objects over increased distances. There are six simple machines:
A pulley is a simple machine that uses grooved wheels and a rope to raise, lower or move a load. An example of a pulley is a block and tackle system on a crane or sailboat.
A lever is a stiff bar that rests on a support called a fulcrum which lifts or moves loads. Levers are classified by the relative positions of the fulcrum and the load or resistance. There are 3 classes of lever. Class 1 has the fulcrum in the middle and examples are seesaws and scissors. Class 2 has resistance in the middle and examples are wheel barrows or bottle opener. Class 3 has resistance on one side and the fulcrum on the other, examples are tweezers.
A wedge is an object with at least one slanting side ending in a sharp edge, which cuts material apart. An example of a wedge is an axe.
A wheel with a rod, called an axle, through its center lifts or moves loads. An example of a wheel and axle is door knob.
An inclined plane is a slanting surface connecting a lower level to a higher level. An example of an inclined plane is a ramp.
A screw is an inclined plane wrapped around a pole which holds things together or lifts materials. An example of a screw is a corkscrew or screw on jar lid.