The following graph describes the motion of a girl going to meet her friend who stays $50\, m$ from her house

$(i)$ How much time she takes to reach her friend's house ?

$(ii)$ What is the distance travelled by the girl during the time$-$interval $0$ to $12$ minute ?

$(iii)$ During which time-interval she is moving towards her house ?

$(iv)$ For how many minutes she was at rest, during the entire journey ?

$(v)$ Calculate the speed by which she returned home.

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 ?

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

An object starting from rest travels $20\, m$ in first $2\,\sec $ and $160\, m$ in next $4\,\sec $. What will be the velocity after $7\,\sec $ from the start ?

What is the nature of the displacement$-$time graph of a body moving with constant acceleration ?