Question

The displacement of a particle as a function of time is shown in the figure. It indicates

• A. the particle starts with a certain velocity, but the motion is retarded and finally the particle stops.
• B. the velocity of the particle decreases.
• C. the acceleration of the particle is in opposite direction to the velocity.
• D. the particle starts with a constant velocity, the motion is accelerated and finally the particle moves with another constant velocity.

Answer 1

Answer: (A), (B), (C)

the acceleration of the particle is in opposite direction to the velocity.

We know that the slope of $S-t$ graph represents velocity.
Initially at origin, slope is not zero, so the particle has some initial velocity.
With increasing time we see that slope is decreasing and finally the slope becomes zero, so the particle stops finally.
As the magnitude of velocity is decreasing, so velocity and acceleration will be in opposite directions.