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You will now learn about, @ Simple machines, , @ Types of simple machines, @ Complex machines, , You must have cut a fruit, tied your shoe, laces, opened a bottle, etc. Do you, remember how you slide down or see-saw, in the park? What makes all these actions, possible? Let us find the answers in this, Chapter., , Simple Machines, It is easy to make a list of all the works that we, cannot do by ourselves. We cannot shift a huge rock or, pull down a tree. We cannot walk all the way to another city or climb all the, stairs of a skyscraper. At times, even work that needs only a little force cannot, , be done by us because we are very tired or unwell or, , may be old., > >) Whenever man found work difficult, he, a) uougl of simpler ways to do it. One of the, 4, , —, , ways he thought of was to invent simple, , , , , = machines. He did not sit about idle but, ’ thought, ‘Let me invent a simple machine., In science, the word ‘machine’ is used for, / any device that helps us to do work, not, iy simply those that run on fuel, = or electricity. A simple machine, is a machine that uses a single, force. It does not increase or decrease the amount of, work but makes it easy by:, , @ Changing the direction of force., , ~ Machines make, work easier, , Machines reduce force, , , , of force needed. Thus, a heavy box becomes easy, to load into a truck if we use a plank. A steep, climb is less tiring if there are steps. Thus, the, plank and the steps are also simple machines.