The machines which are simple in construction and help to make our work easier and faster are called simple machines.

• The ratio of the load to the effort is called the MA of a simple machine.
• A machine having 100 % efficiency is called an ideal machine. No such simple is ideal in real life.
• A lever is a rigid bar. It may be straight or bent, and it rotates about fixed points called a fulcrum.
• There are three classes of a lever based on the location of fulcrum, effort, and load.
• Pulleys are of three types, i) Fixed pulley, ii) Movable pulley, iii) Block and tackle
• The slanted surface is called an inclined plane.
• The wheel and axle are a combination of two cylinders of different diameters.
• A screw is a cylinder having spirally wounded threads around it.
• All cutting and piercing instruments are called wedges.