Thank you for reporting, we will resolve it shortly
Q.
From the following displacement-time graph find out the velocity of a moving body
Motion in a Straight Line
Solution:
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 $v = \tan \,60^{\circ} = \sqrt{3}$
