Question

From the following displacement-time graph find out the velocity of a moving body

• A. $\frac{1}{\sqrt{3}}m/s$
• B. 3 m/s
• C. $\sqrt{3}m/s$
• D. $\frac{1}{3}m/s$

Answer 1

Answer: (C)

In first instant you will apply $v=\tan \theta$ and say

$v=\tan 30^{\circ }=\frac{1}{\sqrt{3}}m/s$

But it is wrong because formula $v=tan\theta$ is valid when angle is measured with time axis.

Here angle is taken from displacement axis. So angle

from time axis $=90^{\circ }-30^{\circ }=60^{\circ }$

Now $v=\tan 60^{\circ }=\sqrt{3}$