Answer:

1.Simple machines are useful because they reduce effort or extend the ability of people to perform tasks beyond their normal capabilities. Simple machines that are widely used include the wheel and axle, pulley, inclined plane, screw, wedge and lever.

2.A lever is a simple machine consisting of a bar that rotates around a fixed point called the fulcrum. Like other machines, a lever makes work easier by changing the force applied to the machine or the distance over which the force is applied.

3.inclined plane, simple machine consisting of a sloping surface, used for raising heavy bodies. The force required to move an object up the incline is less than the weight being raised, discounting friction. The steeper the slope, or incline, the more nearly the required force approaches the actual weight.