Question

A feather is dropped on the moon from a height of $167m$. The acceleration due to gravity on the moon is $1.67m{s}^{-2}$​. Determine the time taken by the feather to fall on the surface of the moon.

• A. $10\sqrt{3}s$
• B. $5\sqrt{2}s$
• C. $10\sqrt{3}s$
• D. $10\sqrt{2}s$

Answer 1

The correct option is D $10\sqrt{2}s$

Given,
distance covered (height) $=167m$,
acceleration $a=1.67m{s}^{-2}$ and
initial velocity, $u=0$

Let the time taken be 't'.
Using the second equation of motion,
$s=ut+\frac{1}{2}a{t}^2$
$167=0+\frac{1}{2}\times 1.67\times t^2$
$\Rightarrow t=\sqrt{\frac{2\times 167}{1.67}}s$
$\Rightarrow t=\sqrt{2\times 100}s$
$\Rightarrow t=10\sqrt{2}s$