Question

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

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

Answer 1

The correct option is C $\sqrt{3}m/s$

In first instant you will apply u=tan$\theta$ and say v=tan ${30}^{\circ }=\frac{1}{\sqrt{3}}m/s$
But it is wrong because the formula $v=tan\theta$ is valid when angle is measured
from time axis.
Here angle is taken from displacement axis. So angle from time axis
${90}^{\circ }-{30}^{\circ }={60}^{\circ }$
Now v=tan ${60}^{\circ }=\sqrt{3}$