What can you say about the motion of a body if its displacement$-$time graph is a straight line parallel to the time axis ?

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.

Draw a velocity versus time graph for a body which starts to move with velocity $'u^{\prime}$ under a constant acceleration $'a'$ for time $t$. Using this graph derive an expression for distance covered $'S'$ in time $'t^{\prime}$

Area under a $v -t$ graph represents a physical quantity which has the unit

$(a)$ Differentiate between speed and velocity.

$(b)$ When is a body said to have uniform velocity ?

$(c)$ How can we describe the position of an object ? Illustrate with suitable example.

How can you find the following ?

$(i)$ Velocity from a displacement$-$time graph.

$(ii)$ Acceleration from velocity$-$time graph.

$(iii)$ Displacement from velocity$-$time graph.

$(iv)$ Velocity from acceleration$-$time graph.