Displacement-time graph of a particle moving in a straight line is as shown in figure.

(a) Find the sign of velocity in regions oa,ab, bc and cd.
(b) Find the sign of acceleration in the above region.

Answer

A, B

Explanation

(a) Velocity=slope of s-t graph
`:.` Sign of velocity=sign of slope s-t graph
(b) Let us discus any one of them, let the portion
cd, slope of s-t graph (=velocity) of this
region is negative but increasing in magnitude.
Therefore sign of velocity and acceleration
both are negative.