Question

A car having a mass of 1 metric ton is moving with a speed of 30 m/s. It suddenly applies the brakes and skids to rest in a certain distance d. The frictional force between the tyres and road is 6000 N. What is the value of d?

(a) 25 m

(b) 50 m

(c) 75 m

(d) 100 m

This question was addressed to me in exam.

Query is from Work-Energy Theorem for a Variable Force in chapter Work, Energy and Power of Physics – Class 11

Answer 1

Right option is (c) 75 m

Easiest explanation: Let; m = 1000 kg

From Work-Energy theorem

Kf – Ki = F * d

0 – (1/2 * m * v^2) = -6000 * d

1/2 x 1000 x 30^2 = 6000 x d

d = 75 m.