A pair of scissors is two levers put together. With this simple machine, less force is needed because a greater distance is involved. Other types of levers include a see-saw, a hammer, a fork and a baseball bat.Know More
There are several other categories of simple machines. An inclined plane has a small force applied over a large distance. Ramps, ladders and stairs are inclined planes. Both wedges and pulleys make work easier by changing the direction of the force. Knives, nails and axes function as wedges, while a flag-raising system needs a pulley. The simple machine "wheel" is a combination of a circular object and an axle. Door knobs and bike pedals are examples of wheels. A screw is a type of inclined plane. A jar and lid, a helicopter blade and a boat propeller are all variations of screws.