Question

When a car driver travelling at a speed of 10m/s applies brakes and brings the car to rest in 20 s,then retardation will be:

Answer 1

A car driver is traveling at a speed of 10m/s .
e.g., initial velocity , u = 10m/s
He applied break and brings to the car to rest in 20s.
so, time taken to stop the car = 20s
we have to find retardation.
final velocity of car , v = 0

use formula, v = u + at
0 = 10 + a20
a = -1/2 m/s² [hereative sign shows retardation ]

Answer 2

Answer:

-0.5 m/s²

Explanation:

given,

v = 0 m/s  (since the car comes to rest)

u = 10 m/s

t = 20 seconds

acceleration = (v-u)/t

                     = (0-10)/20

                     = -1/2

acceleration = -0.5 m/s²

We know that, negative acceleration is also known as deceleration or retardation.

Therefore,

deceleration/retardation = 0.5 m/s²