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5.Work, Energy, Power and Collision
normal
A particle of mass $m$ at rest is acted upon by a force $P$ for a time $t.$ Its kinetic energy after an interval $t$ is
A
$\frac{{{P^2}{t^2}}}{m}$
B
$\frac{{{P^2}{t^2}}}{2m}$
C
$\frac{{{P^2}{t^2}}}{3m}$
D
$\frac{{{P}{t}}}{2m}$
Solution
$\mathrm{v}=\mathrm{u}+\mathrm{at}$ $P=m a$
$\mathrm{v}=\mathrm{at} \quad \ldots(1)$ $a=\frac{P}{m} \ldots(2)$
$v = \frac{p}{m} \times t$
$\mathrm{KE}=\frac{1}{2} \mathrm{mv}^{2}=\frac{1}{2} \times \mathrm{m} \times \frac{\mathrm{P}^{2}}{\mathrm{m}^{2}} \times \mathrm{t}^{2}$
$\mathrm{KE}=\frac{\mathrm{P}^{2} \mathrm{t}^{2}}{2 \mathrm{m}}$
Standard 11
Physics
