Question

Brakes are applied to a car moving with disengaged engine bringing it to a halt after 2sec its velocity at the moment when the breaks are applied if the coefficient of friction between the road and the tyres is 0.4 is

Answer 1

The car comes to rest and therefore the final velocity is zero.

The Force acting on the car is :

Force = mg × coefficient of friction

Force = 10m × 0.4 = 4m

F = ma

4m = ma

a = 4

From the following equation of motion :

V = u - at

0 = u - (4 × 2)

0 = u - 8

u = 8

The initial velocity is :

= 8 m/s

Answer 2

Explanation:

v=u+at

a=friction.g

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