Question

A body is projected with an initial velocity 20 m/s at ${60}^{\circ }$ to the horizontal. Its initial velocity vector is _______ $(g=10m/s^2)$

• A. $10i-20j$
• B. $10\sqrt{3i}+10j$
• C. $10i+10\sqrt{3}j$
• D. $5i+5\sqrt{3}j$

Answer 1

Answer: (C)

$10i+10\sqrt{3}j$

Its initial velocity in the $x$-direction is $20$cos${60}^0$

$=\frac{20}{2}=10m/s.$

initial velocity in $y$ direction $20$ cos${60}^0=\frac{20\sqrt{3}}{2}=10\sqrt{3}m/s$.

So,

velocity vector is $10\hat{i}+10\sqrt{3}\hat{j}$.