A particle covers a distance from A to B over a period of time, the distance versus time plot is the shown below. Then which of the following is true for the motion of the particle?

Options

A. Both average speed and instantaneous speed are always zero
B. Average speed is always non-zero but instantaneous speed can be zero
C. Instantaneous speed is always non-zero but average speed can be zero.
D. Both average speed and instantaneous speed are always non-zero.

Answer

B

Explanation

The distance versus time plot for movement of a particle from A and B is shown in the diagram.

From graph, it is a slope of distance-time graph for position A to C and D to B is always positive, therefore both the average speed and instantaneous speed are not always zero, therefore, option (a) is not correct.
Average velocity ` = ("Total displacement from A to B ")/("Total time interval")`
Since, total displacement depends on straight distance between initial and final points, hence, displacement between A to B always non zero, therefore the average speed is always non zero. Since, no distance is travelled between point to D is zero. Hence, instantaneous speed at every instant between C to D is zero. Hence, option (b) is correct and option (c) and (d)