If the displacement of a body is proportional to the time elapsed, what type of motion does the body possess ?

The slope of the line on a position-time graph reveals information about an object's velocity. What conclusion can you draw regarding the motion of an object, if the graph is a

$(i)$ Horizontal line.

$(ii)$ Straight diagonal line.

$(iii)$ Curved line.

All buses and cars these days are fitted with a speedometer, which shows the velocity of the vehicle. A device called odometer records the distance moved by the vehicle. If the reading on the odometer of a vehicle in the beginning of a trip and after $40$ minutes were $1048\, km$ and $1096\, km$ respectively, calculate its average velocity. Will the reading on the speedometer show this velocity when the vehicle is moving ? Support your answer with reason.

Mention some uses of velocity$-$time graphs.

Ali while driving to school computes the average speed for his trip to be $20\, km h^{-1}$. On his return trip along the same route there is less traffic and the average speed is $30\, km h^{-1} .$ What is the average speed for Ali's trip ?