Question

The minimum stopping distance of a car moving with velocity $v$ is $x$. If the car is moving with velocity $2v$, then the minimum stopping distance will be

• A. $2x$
• B. $4x$
• C. $3x$
• D. $8x$

Answer 1

The correct option is B $4x$

Let retarding force is $F$ and given stopping distance is $x$

From work energy theorem

$Fx=\frac{1}{2}m{v}^2$

and $F\left(x^{\prime }\right)=\frac{1}{2}m(2v{)}^2$

Solving these two equations, we get
$x^{\prime }=4x$