__How and
why things move: Formulae__

Some formulae will be given to you in the
examination. You will need to remember other formulae. In both situations
you will need to know how to apply and use the formulae. Always (i) write
down the formula, (ii) show your working, and (iii) give the answers with
units. You might find it easier to use symbols to remember these
formulae

__I need to
remember these .....__

**momentum = mass × velocity**

** **

**change of momentum = resultant force x time for which
it acts**

** **

**Work done = resultant force x distance moved**

** **

**change in gravitational PE =
weight x vertical height
difference**

** **

**kinetic energy = ½ x
mass x [velocity] ^{2}**

**Average speed = gradient of a distance-time
graph**

__I will be given this formula:__

**Average speed =
distance moved **

**
time taken **

** **

** **