Question

A body is projected horizontally from the top of a high tower with a speed of $20m{s}^{-1}$. After $4$ seconds, the displacement of the body is
$(g=10m{s}^{-2})$

• A. $40m$
• B. $80m$
• C. $80\sqrt{2}$m
• D. $\frac{80}{\sqrt{2}}$m

Answer 1

Answer: (C)

$80\sqrt{2}$m

$\upsilon =20m/s$
$t=4sec$
$s_h=v_h\times t=20\times 4=80m$
${\upsilon }_v=0$
$g=10m/s^2$
$t=4sec$
$s_v=\frac{1}{2}\times 10\times 4\times 4$

$s_v=80m$
Displacement, $d=$ $\sqrt{s_v^2+s_n^2}=80\sqrt{2}m$