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Define work. What is its SI unit?
Work:
Work is done when a force acting on a body displaces it in the direction of a force. Work is a scalar quantity. It depends on the force acting on a body, displacement of the body, and the angle between them.
Work done = Force x displacement
Or W = F S........ (i)
W = $F_{x} \times S$
W = $(F cos \theta) S$
W = $FS cos \theta$ ........(ii)
Unit of work:
SI unit of work is the joule (J). it is defined as
The amount of work is one joule when a force of one newton displaces a body through one meter in the direction of the force.
Thus $1 J = 1 N \times 1 m$
When does a force do work? Explain.
Work is said to be done when a force acts on a body and moves it in the direction of the force. Greater is the force acting on a body and the the the longer is the distance moved by it, the the the larger would be the work done. Mathematically, Work is a product of force F and displacement S in the direction of the force. Thus
Work done = Force x displacement
Or W = F S .........(i)
If the force is unbalanced, it causes acceleration. This involves doing work to move it in a certain direction.
Why do we need energy?
Need for energy:
Energy is a fundamental concept in science. It links almost all the natural phenomena. When we say that a body has energy, we mean that it can do work, so it possesses energy. The energy from running water can be used to run the water mills or water turbines.
Energy exists in various forms such as mechanical energy, heat energy, light energy, sound energy, electrical energy, chemical energy, nuclear energy, etc. Energy can be transformed from one form into another.
