Question

A ball at rest is dropped from the top of a mountain. What is the distance travelled by the ball in the first two seconds? ( Take acceleration due to gravity $g=9.8m{s}^{-2}$)

• A. $20m$
• B. $19.6m$
• C. $39.2m$
• D. $18.33m$

Answer 1

The correct option is B $19.6m$

Given,
Initial velocity $u=0$ (since the ball is at rest initially)
Acceleration due to gravity $g=9.8m{s}^{-2}$
Time $t=2s$
Let the distance travelled by ball in $2$ seconds be $s$ metres.
From equation of motion,
$s=ut+\frac{1}{2}g{t}^2$
$s=0\times 2+\frac{1}{2}\times 9.8\times 2^2$
$\therefore$ Distance covered by ball in 2 seconds is $s=19.6m$