# Deceleration Formula

You must have noticed that often we slow down the speed of our bikes during heavy traffic when more bikes are obstructing us. So, a decrease in speed as the body moves away from the starting point is defined as Deceleration.

It is expressed as

$Deceleration=\frac{Final\,&space;time-Initial\,&space;time}{Time\,&space;taken}$

Deceleration also is known as negative acceleration. Hence it is denoted by – a.

If starting velocity, final velocity and time taken are given, Deceleration Formula is given by

$a=\frac{v-u}{t}$

If initial velocity, final velocity and distance travelled are given, deceleration is given by

$a=\frac{v^{2}-u^{2}}{2s}$

Where,

v = final velocity,

u =  initial velocity,

t = time taken,

s = distance covered.

Deceleration Formula is used to calculate the deceleration of the given body in motion. It is expressed in meter per second square (m/s2).

## Solved Examples

Question 1: An automobile moving with a uniform velocity of 54 Kmph is brought to rest in travelling a distance of 5 m. Calculate the deceleration produced by brakes?

Solution:

Given: Initial velocity u = 54 Kmph,

Final velocity v = 0

Distance covered s = 5m

We know that v2 = u2 + 2as

Deceleration a = v2 u2 / 2s

= – (54000 )2 / 2(5)

a=-291.6 x 10m/s2