Question

A body at rest starts sliding from top of a smooth inclined plane and requires $4$ seconds to reach bottom. How much time does it take, starting from rest at top, to cover one-fourth of a distance?

• A. $1$ second
• B. $2$ seconds
• C. $3$ seconds
• D. $4$ seconds

Answer 1

The correct option is B $2$ seconds

Let acceleration be $a$ and length of incline be $l$.

We assume that acceleration down the inclined plane is constant.

So, by kinematics relations, we have:

$0.5a\times 16=l⟹a=\frac{l}{8}\frac{1}{2}\times \frac{l}{8}{t}^2=\frac{l}{4}⟹t=2$