Question

51. When a car driver travelling at a speed of 10 m/s applies brakes and brings the car to rest in 20 s, the
retardation will be
(a) + 2 m/s2
(by- 2 m/s2
(C) - 0.5 m/s2
52. Which of the following could not be a unit of speed ?
(d) + 0.5 m/s2​

Answer 1

Question :-

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

Given :-

• u = 10 m/s
• v = 0 m/s
• t = 20 s

To find :-

• Retardation

Solution :-

Substituting the values in 1st equation of motion :-

v = u + at

0 = 20 + 20a

20a = -20

a = -1 m/s²

Retardation = 1 m/s²