A body of mass 10 kg at rest is acted upon

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A body of mass $10\,kg$ at rest is acted upon simultaneously by two forces $4 \,N$ and $3\,N$ at right angles to each other. The kinetic energy of the body at the end of $10 \,sec$ is .............. $\mathrm{J}$

A

$100 $

B

$300$

C

$50$

D

$125 $

A body of mass $10\,kg$ at rest is acted upon simultaneously by two forces $4 \,N$ and $3\,N$ at right angles to each other. The kinetic energy of the body at the end of $10 \,sec$ is .............. $\mathrm{J}$

Net force on body$ = \sqrt {{4^2} + {3^2}} = 5N$
$a = F/m = 5/10 = 1/2\,m/{s^2}$
Kinetic energy = $\frac{1}{2}m{v^2}$$ = \frac{1}{2}m{(at)^2} = 125\,Joule$