Question

when a car driver travelling at a speed of 10 metre per second applies brakes and brings the car to rest in 20 seconds then retardation will be:
a)+2m/second square
b)-2m/s^2
c)+0.5m/s^2
d)-0.5m/s^2

Answer 1

Answer:

THE ANSWER IS

c)-0.5m/s^2

Answer 2

Answer:

The retardation for the car will be -0.5m/s² i.e.option (d).

Explanation:

We will solve this question by the kinematics of the first equation of motion i.e.

$v=u+at$       (1)

Where,

v=final velocity of the body

u=initial velocity of the body

a=acceleration produced by the body

t=time taken

From the question we have,

u=10m/s

v=0                 (as brakes are applied and the car is brought to rest)

t=20 seconds

By substituting the value of u,v, and t in equation (1) we get;

$0=10+a\times 20$

$a=\frac{-10}{20}=-0.5m/s^2$              

Hence, the retardation for the car will be -0.5m/s² i.e.option (d).