A-level 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 (EK) is moving energy and potential energy (EP)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