The displacement-time graph of a body is parallel to the time axis. What will you infer about the velocity of the body?

The distance-time graph of a body is a straight line inclined to the time axis. The body is in:

What do you understand by the displacement-time graph? Draw a displacement-time graph for a girl going to school with uniform velocity. How can we calculate the uniform velocity from it?

From the given $v-t$ graph (Fig.),it can be inferred that the object is

The velocity-time graph of a truck is plotted below.
$(a)$ Calculate the magnitude of displacement of the truck in $15$ seconds.
$(b)$ During which part of the journey was the truck decelerating?
$(c)$ Calculate the magnitude of average velocity of the truck.

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.