What does the slope of a displacement$-$time graph represent ? Can displacement$-$time sketch be parallel to the displacement axis ? Give reason to your answer.

A car travels $100\, km$ east and then $100 \,km$ south. Finally, it comes back to the starting point by the south-east route. Throughout the journey the speed is constant at $60\, km h ^{-1}$. The average velocity for the whole journey if time taken is $3.3$ hours is

A train starting from rest picks up a speed of $10\, m s ^{-1}$ in $100\, s$. It continues to move at the same speed for the next $250\, s$. It is then brought to rest in the nert $50\, s$. Plot a speed$-$time graph for the entire motion of the train.

$(i)$ acceleration of the train while accelerating,

$(ii)$ retardation of the train while retarding,

$(iii)$ and the total distance covered by the train.

$(i)$ What can be depicted from the graph regarding the motion of the object ?

$(ii)$ Find the value of acceleration from the graph.

Can a particle be accelerated

$(i)$ if its speed is constant ?

$(ii)$ if its velocity is constant ?