Question

$KE$ acquired by a mass $m$ in travelling a certain distance $d$, starting from rest, under the action of a constant force $F$ is

• A. Directly proportional to $\sqrt{m}$
• B. Directly proportional to $m$
• C. Directly to proportional to $\frac{1}{m}$
• D. $Noneofthese$

Answer 1

The correct option is D $Noneofthese$

Given:
$u=0$
$F=ma\therefore a=\frac{F}{m}s=ut+\frac{1}{2}a{t}^2$
$v=u+at0+\frac{F}{m}tt=\sqrt{\frac{2Dm}{F}}$
$KE=\frac{1}{2}m{v}^2=\frac{1}{2}m\frac{F^2}{m^2}{t}^2=\frac{1}{2}m\frac{F^2}{m^2}\times \frac{2Dm}{F}$
$KE=F.D$
independent of $m$