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V Science 11. Simple Machines, , > simple machines wedge hoist wheelchairs, complex machines crowbar knife screw, vacuum cleaners lever pliers bicycles, inclined plane beam balance lawn mowers ramps, washing machines __ pulley fulcrum wheel and axle, Answer these questions :, 1) What is a simple machine? List the various types of simple machines?, , A: Amachine that consists of few or no moving parts is called a simple machine., A bottle opener, a knife, a ramp and a wheel are some examples of simple, machines. The various types of simple machines are the lever, the inclined, plane, the pulley, the wheel-and-axle, the screw and the wedge., , 2) What is a pulley? How does it make our work easy?, , A: Apulley consists of a wheel that is free to rotate about an axle passing through, its centre. The rim of the wheel has raised edges. A rope or a string passes, through the rim. A pulley is used to lift or move heavy objects. In a pulley, the, axle is fixed on a rigid support such as a wall. One end of the rope passing, over the pulley is tied to the load. The effort is applied at the other end of the, rope. A pulley makes our job easy by changing the direction of force applied., , 3) | What is a screw? Describe its use., A: Ascrew isa long nail with a spiral metal thread along its length. We usually, , , , , , , , , use screws to join two pieces of wood together. A screw holds the pieces, together more firmly than a nail does. The head of the screw has a groove, where a screwdriver can be fixed. With every turn of the screwdriver, the, screw moves easily into the wood., , _Whati is a wedge? How does it work as a simple machine?, , edge is a piece of wood or metal shaped like a triangle. A wedge can be, two inclined planes together, back to back. It has a thick edge