Science project idea on what is meant by work and force.
Work and Force Science Project Idea 
What is meant by work and force. We have already defined energy as the power to do work, but just what do we mean by doing work? A man who digs a ditch or shovels coal is doing work. Steam which moves a piston, which in turn operates a pump, which lifts water to a tank on the roof, does work. This water in turn, we know, as it descends may operate a motor which will run a sewing machine or a churn, or may generate electricity which may run a motor, or be changed into heat to be used again in boiling water to produce steam. In raising the water, work is being done; also in the movement of the parts of the sewing machine or churn or dynamo, work is being done. The essential of all these examples of work is that there is the movement of a material thing through space against some resistance. What is the resistance that is overcome in lifting the water to the roof? In the sewing machine it is the inertia (the tending of a body to remain in the condition in which it is), the friction of the parts of the machine, and the friction of the needle as it passes through the cloth. In the same way, the electricity in moving the parts of the motor against resistance is doing work.
A boy who lifts a ten pound weight from the floor to a table is doing work. If the boy holds the weight he is doing no work, although the muscles of his arms may become very tired. He is, however, exerting sufficient force to resist the force of gravity upon the ten pound body. Since the body is neither raised nor lowered, the force he is exerting must be equal to the amount of the pull of gravity upon it .
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