P2.2.1 - AQA GCSE Physics Unit 2

P2.2.1	Forces and energy
	a) When a force causes an object to move through a distance work is done.
	b) Work done, force and distance are related by the equation: W = F x d	W is the work done in joules, J F is the force applied in newtons, N d is the distance moved in the direction of the force in metres, m
	c) Energy is transferred when work is done.	Candidates should be able to discuss the transfer of kinetic energy in particular situations. Examples might include shuttle re-entry or meteorites burning up in the atmosphere.
	d) Work done against frictional forces.
	e) Power is the work done or energy transferred in a given time. P = E/t	P is the power in watts, W E is the energy transferred in joules, J t is the time taken in seconds, s
	f) Gravitational potential energy is the energy that an object has by virtue of its position in a gravitational field. E_p = m x g x h	Candidates should understand that when an object is raised vertically work is done against gravitational force and the object gains gravitational potential energy. E_p is the change in gravitational potential energy in joules, J m is the mass in kilograms, kg g is the gravitational field strength in newtons per kilogram, N/kg h is the change in height in metres, m
	g) The kinetic energy of an object depends on its mass and its speed. E_k = ¹/₂ mv²	E_k is the kinetic energy in joules, J m is the mass in kilograms, kg v is the speed in metres per second, m/s