Question

The driver of a 800 kg car travelling with a speed of 54 kilometre per hour on a highway sees a child on the road applies the brakes to save the child breaks exert a retarding force of 5000 Newton calculate the time interval during which the car stops?​

Answer 1

V(car) = 54 km/h = 15 m/s

M(car) = 800 kg

F(retardation) = - 5000 N

Negative symbol represents direction of acceleration

retardation (-a) = - 5000 / 800 = - 6.25 m/s^2

Distance travelled by car before it stops say 's'

v(final) = 0

v(initial) = 15 m/s

v^2 - u^2 / 2 (a) = s

0 - 225 / 2 ( - 6.25) = 18 m

now,

v = u + at

0 = 15 - 6.25t

15 = 6.25t

t = 15/6.25

t = 2. 4 seconds

Answer 2

Explanation:

try to solve by ownself

not to cheat