Question

A car is moving on a straight line with speed 54km/h. It is stopped in 8sec by applying the brakes. (I)Find the speed of car in m/s (ii) Retardation(iii) The speed of car after 3sec of applying the brakes.​

Answer 1

Explanation:

Given:-

Speed = 54km/hr

time to stop = 8 sec

final velocity = 0m/s

i) Solution i:-

we know

1 km = 1000m

1hr = 3600 sec

Converting 54 km/hr to m/s

=(54*1000)/3600

=15 m/s

ii) Solution ii:-

a = (v - u)/t

= (0 - 15)/8

= -15/8

retardation = - 7.5m/s^2

iii) Solution iii:-

v = u + at

v = 15m/s + (- 7.5) 3

v = 15m/s - 22.5

v = 7.5 m/s