Question

A car moving with speed u can be stopped in minimum distance x when brakes are applied. If the speed becomes n times, the minimum distance over which the car can stopped would take the value

• A. $\frac{x}{n}$
• B. $nx$
• C. $\frac{x}{n^2}$
• D. $n^{2}x$

Answer 1

The correct option is D $n^{2}x$

$v^2=u^2-2ax$

$0=u^2-2ax$

$x=\frac{u^2}{2a}$

$x^{\prime }=\frac{(nu{)}^2}{2a}=\frac{n^2{u}^2}{2a}$

$x^{\prime }=n^{2}x$