Question

A body at rest starts sliding down on a smooth inclined plane. It slides down $\frac{1}{4}th$ distance in 2s. It will slide down the complete plane in

• A. $4s$
• B. $5s$
• C. $2s$
• D. $3s$

Answer 1

Answer: (A)

$4s$

Assumption: Initial velocity of the body is zero.

The body will slide down with a constant acceleration as the force acting on the body is constant.

Using second equation of motion,

$s=ut+\frac{1}{2}a{t}^2$

Let the total distance along the plane be $L$.

Then, for one-fourth of the distance,

$\frac{L}{4}=\frac{1}{2}a\times 2^2..........\left(i\right)$

For complete distance,

$L=\frac{1}{2}a\times t^2..........\left(ii\right)$

Using (i) & (ii), $t=4s$