# What is the change of speed over time?

1. Jul 25, 2006

2day i started a new topic inj physics and there were a few terms which i am unsure of. if velocity is the change of displacement over time, and acceleration is the change of velocity, and if speed is the change of distance over time, what is the change of speed over time? also i have come across a few formulas for this topic, these formulas are listed below
$$s = ut + \frac{1}{2} at^2$$

$$v = u + at$$

$$v^2 = u^2 - 2as$$

$$v_{average} = \frac{s}{t}$$

$$a_{average} = \frac{v - u}{t}$$

are these all the formulas that are required for this topic or are there more? i understand that in some cases they may need to be rearanged.
many thanks,

2. Jul 25, 2006

### Hootenanny

Staff Emeritus
The rate of change of speed with respect to time is often termed acceleration, although I do not care for its use. The the formulae you list are valid for constant acceleration in kinematics (except the average acceleration as that obviously can be used universally). The formulae are all that are required for basic kinematics however, there is a further formulae, $s = \frac{1}{2}(u+v)t$, that may be useful but it is derived from the above formulae.

3. Jul 26, 2006