What do you mean by positive acceleration?

Figure given shows the displacement-time graph of four children $\mathrm{A}, \mathrm{B}, \mathrm{C}$ and $\mathrm{D}$. Which child has the highest velocity?

A cyclist travels a distance of $4 \mathrm{km}$ from $\mathrm{A}$ to $\mathrm{B}$ and then moves a distance of $3 \mathrm{km}$ at right angle to $\mathrm{AB}$. Find his resultant displacement and total distance travelled.

Velocity of a particle moving along a straight line in a certain time interval is shown in figure given. What is the distance travelled during acceleration?

Explain the differences between the two graphs shown in the figure.

A flyover is $500 \mathrm{m}$ long. A $10 \mathrm{m}$ long bus crosses the flyover at a speed of $30 {\mathrm{ms}}^{-1}$. Find the time taken by the bus to cross it.

The velocity-time graph represents motion of an object for $350 \mathrm{s}$. 
Calculate acceleration of the object for the time internal $100 \sec <\mathrm{t}<200 \sec$