A car , moving with a speed of `50 km//hr` , can be stopped by brakes after at least ` 6m `. If the same car is moving at a speed of `100 km//hr`, the minimum stopping distance is

Options

A. 6 m
B. 12 m
C. 18 m
D. 24 m

Answer

D

Explanation

Using `v^2 = u^2 + 2as`. If car is retarding and final velocity becomes zero. Then, the equation becomes
`0 = u^2 - 2 as rArr s = (u^2)/(2a)` or `s prop u^2`. Now speed is two times so distance will be four times. i.e., `S = 4 xx 6 = 24 m`.