Question

Tripling the speed of a motor car multiplies the distance needed for stopping it by

• A. 3
• B. 6
• C. 9
• D. some other number

Answer 1

The correct option is C 9

Relation between velocity and distance is

$V^2=U^2+2aS$

If the final velocity Zero then the relation is become
$U=\sqrt{2aS}$

Now if we want to multiply the velocity 3 time then we have to multiply the distance 9 time to make the equation balanced.