Physics: Acceleration

Getting acceleration (like speed) requires division.

a = v / t is an equation for finding acceleration. It means: a (acceleration) is is found by dividing the v (velocity or speed) by the time it takes.

Say your going 65 km/h on a flat road, then suddenly an animal runs onto the road. You hit the breaks and it takes you 15 seconds to come to a complete stop: 0 km/h. What was your deceleration.
2
You don't want a number less than 1 so you decide to put it cm/sec *.

First, convert km/h to km/s by dividing it by 60 because there are 60 minuets in an hour to get: 1.08. Then divide that by 60 because there are 60 seconds in a minute to get: 0.01.

Next, multiply that by 1000 to get m/s and then by 100 to get cm/s: 1805.5.
2
Finally, divide that by 15 to get -120.3** cm/s.
2
That's that. The deceleration is -120.3 cm/s.


*The act of dividing velocity by time makes the denominator squared.
**It is negative because the speed is decreasing.

Sources:
Physics workbook for dummies.