Question

Similar balls are thrown vertically each with a velocity $20m/s$, one on the surface of earth and the other on the surface of moon. What will be ratio of the maximum heights attained by them? $($Acceleration on moon $=\frac{g}{6}m/s^2$ approximately, where $g$ is gravitational acceleration due to earth$)$

• A. $6$
• B. $\frac{1}{6}$
• C. $\frac{1}{5}$
• D. None of these

Answer 1

Answer: (B)

$\frac{1}{6}$

Since $v{}^2=u{}^2+2as$ .......(1)

For first case $u_1=20m/s,v_1=0,a_1=g=-10m/s^2,s_1=?$
From equation (1)

$s_1=\frac{u_1^2}{2\times g}$

So $s_1=\frac{400}{2\times 10}=20m$

For second case (at moon) $u_2=20m/s,v_2=0,a_2=\frac{g}{6}$

Similarlly,

$s_2=\frac{u_2^2}{2\times g}$

$s_2=\frac{400}{2\times 10/6}$

Now,

So $\frac{s_1}{s_2}=\frac{1}{6}$