Alevel Physics/Forces, Fields and Energy/Work and energy
Doing Work:
Work is done whenever a force moves something over a distance. The force moves through a distance, and we say that it does work. The amount of work done tells us the amount of energy that has been transferred by the force. Thus:
work done (J) = energy transferred (J)
To calculate the amount of work done W, we need to know two quantities:
 The magnitude of the force F.  The distance, d, moved by the force, in the direction of the force/parallel to the force.
So Work done = force × distance moved in the direction of the force .
or, where is the angle between the direction of the force and the distance,
Force is measured in and distance travelled parallel to the force in . Thus, Work done is described in newton metres or . This is the SI unit, joule, . work done by tension &= T \times D\\ work done against friction &= F \times D\\ work done by gravity &= mg \times h\\ \end{alignat} </math>
Energy:
James Joule is the man, where the term 'the joule' comes from. His principle of conservation of energy states that:
While energy may be converted from one form to another, the total amount of energy in a closed system is always constant.
There are two main different types of energy; kinetic and potential. Kinetic energy (E_{K}) is moving energy and potential energy (E_{P})is the energy that could be transferred to moving energy. The formula for these are:
Kinetic Energy:
Potential Energy:
The relationship between work done and energy is:
Work done = Energy transferred
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