Question

Stopping distance of a moving vehicle is directly proportional to

• A. square of the initial velocity
• B. square of the initial acceleration
• C. the initial velocity
• D. the initial acceleration

Answer 1

Answer: (A)

square of the initial velocity

Answer 2

Let $d_s$ is the distance travelled by the vehicle before it stops. Here, final velocity $v = 0$, initial velocity $= u$, $S = d_s$ Using equation of motion $v^2=u^2+2aS$ $\therefore \left(0\right)^{2}=u^{2}+2ad_{s}$; $d_{s}=-\frac{u^{2}}{2a}$ or $d_{s} \propto u^{2}$