Question

An automobile, travelling at $40km/h$, can be stopped at a distance of $40m$ by applying brakes. If the same automobile is travelling at $80km/h$, the minimum stopping distance, in metres, is (assume no skidding)

• A. $75m$
• B. $160m$
• C. $100m$
• D. $150m$

Answer 1

The correct option is B $160m$

Since stopping distance, $s=\frac{v^2}{2a}$

For case 1, $40=\frac{(40\times \frac{5}{18}{)}^2}{2a}$...............(1)

For case 2, $s=\frac{(80\times \frac{5}{18}{)}^2}{2a}$..................(2)

From (1) and (2), $s=160m$