Energy Concepts

1.3.1 Energy

1.3.2 Work
Work done is de ned as the force multiplied by the distance moved in the direction of the force, with formulae:
Work done = Force×distance moved in the direction of the force
W = F ×x
(J) = (N)(m)


Please note that this is not in the formula booklet.
W = Fxcosθ
(J) = (N)(m)
This however, is. And work done is equal to the change in energy:

1.3.3 Hooke’s Law
Hooke’s Law states that the load applied to an object is directly proportional to the extension, provided that the elastic limit is not reached, and as such:

where k is the spring constant The force and extension can be used to nd the elastic potential energy gained:

1.3.4 E ciency
E ciency is de ned as the amount of useful energy obtained per energy input, with formula: