This book has seven chapter. What is a machine?, the lever, the wedge, the screw, the wheel and axle, and the pulley. A machine is a tool that makes work easier to do. And, they’re made our lives wealthy. Simple machines have a lot of kinds. For example, there are tool moving the whole, and that moving the part of thing. The lever is simple machine too. It’s used to lift objects that is heavy. This related to fulcrum, effort, and load. We can carry ten bricks by monocycle, this also use the principle of leverage. We use inclined plane at the time to carry a load to higher level from lower level. Then, ramp is convenient when the person who stepped on the wheelchair moves. People use the pointed edge of a wedge to split things apart. And the axe head can cut through wood, and the chisel can cut through wood with a hammer can also cut through stone. The screw is helped when we hold objects. The axle is made up of wheels. When either the wheel or axle is turned, the other part also turns, making work easier. The pulley is like the wheel and axle. At the end of the rope or chain is a hook that can be attached to a heavy object. All of these tool was made by ancient people. The wisdom of the old person is grate!
(236 words)
(Carmel Reilly/Simple Machines/2007/NELSON CENGAGE Learning)
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