Question

A particle of mass $m$ at rest is acted upon by a force $F$ for a time $t$, its kinetic energy after an interval $t$ is :

• A. $\frac{F^2{t}^2}{m}$
• B. $\frac{F^2{t}^2}{2m}$
• C. $\frac{F^2{t}^2}{3m}$
• D. $\frac{Ft}{2m}$

Answer 1

Answer: (B)

$\frac{F^2{t}^2}{2m}$

We know ,

$F=ma$ ; $v=u+at,u=0;a=\frac{v}{t}$

$v=\frac{Ft}{m}$

$K.E=\frac{1}{2}m{v}^2$

$=\frac{1}{2}m(\frac{Ft}{m}{)}^2$

$=\frac{F^2{t}^2}{2m}$