Question

A body of mass 2 kg has an initial velocity of 3 m/s along x-axis and it is subjected to a force of 4 N in y-direction. The distance of the body from origin after 4 seconds will be: (the body was subjected to force at the origin at t= 0 )

• A. 12 m
• B. 28 m
• C. 20 m
• D. 48 m

Answer 1

Answer: (C)

$u_{x}=3 \,ms^{-1} , as =0, u_{y}=2m/sec^{2}$ and $t=4$ sec
If $s_{x}$ an $s_{y}$ be the displacement along x-axis and y-axis respectively then
$S_{x}=u_{x}t+\frac{1}{2}a_{x}t^{2} $
$=3\times4+\frac{1}{2}\times0\times\left(4\right)^{2}=12 m$
and $s_{y}=u_{y}t+\frac{1}{2}a_{y} t^{2} $
$=0\times4+\frac{1}{2}\times2\times\left(4\right)^{2}=12$ m
$s=\sqrt{s_{x}^{2}+s_{y}^{2}}=\sqrt{\left(12\right)^{2}+\left(16\right)^{2}}$
$=\sqrt{144+256}=\sqrt{400}=20 \,m$