Area under a speed-time graph is equal to the

$A$ girl walks along a straight path to drop a letter in the letterbox and comes back to her initial position. Her displacement-time graph is shown in the figure. Plot a velocity-time graph for the same.

$A$ moving body is covering a distance directly proportional to the square of time. The acceleration of the body is

Mention some uses of velocity-time graphs.

If the acceleration of a particle is constant in magnitude but not in direction,what type of path is followed by the particle?

The graph given below is the distance-time graph of an object.
$(i)$ Find the speed of the object during the first four seconds of its journey.
(ii) How long was it stationary?
(iii) Does it represent a real situation? Justify your answer.