Acceleration
Acceleration is defined as follows:
\(acceleration= \frac{\Delta v}{time taken}\)
\(\Delta v\) (pronounced 'delta v' is the change in speed of the object.
Acceleration is measured in metres per second per second or metres per second squared \(m\, s^{-2}\).
How to measure acceleration of an object:
- measure instantaneous speed of object at two points (point A and point B) on route
- measure time for object to travel between point A and point B
- find change in speed of object between point A and point B
- divide change in speed by time taken for change to happen
Example
Question
A sprinter starting at \(0\,m\, s^{-1}\) in the blocks, reaches a speed of \(10\, m\, s^{-1}\) in 4 seconds. Calculate the acceleration.
\(a=\frac{\Delta v}{t}\)
\(= \frac{10}{4}\)
\(=2.5\, m\, s^{-2}\)
We sometimes refer to a moving object as having a 'constant acceleration' or a 'uniform acceleration'. A constant or uniform acceleration means that the speed of the object changes by the same amount every second.
Acceleration and force
If an object is slowing down, when the acceleration is calculated, the answer is negative.
