Question

Q.6 - When a car driver travelling at a speed of 10 m/s applies brakes and
brings the car to rest in 20 s, then the retardation will be:
(a) + 2 m/s
(b) – 2 m/s
(c) 0.5 m/s?
(d) + 0.5 m/s​

Answer 1

Given :

• Initial velocity (u) = 10 m/s
• Final velocity (v) = 0 m/s
• Time (t) = 20 seconds

To find :

• Retardation

According to the question,

By using Newton's first equation of motion we will find retardation

→ v = u + at

→ 0 = 10 + a × 20

→ -10 = 20 a

→ -10 ÷ 20 = a

→ - 0.5 = a

So,the retardation will be 0.5 m/s²..

As negative signs means retardation.

So,the correct option is c) 0.5 m/s²

_________...

First equation of motion :

• v = u + at

Second equation of motion :

• s = ut + ½ at²

Third equation of motion :

• v² = u² + 2as

• v stands for Final velocity

• u stands for Initial velocity

• t stands for Time

• a stands for Acceleration

• s stands for Distance