"$v=u+at$ is used in case of variable acceleration". Comment.

State which of the following situations are possible and give an example of each of these:

(a) A body having acceleration but zero velocity.

(b) A body moving horizontally with an acceleration in a vertical direction.

(c) A body moving with a constant velocity in an accelerated motion.

A body moves with a velocity of $2 {\mathrm{ms}}^{-1}$ for $5 \mathrm{s}$. Then its velocity increases uniformly to $10 {\mathrm{ms}}^{-1}$ in next $5 \mathrm{s}$. Thereafter, its velocity begins to decrease at a uniform rate until it comes to rest after $10 \mathrm{s}$. Plot a velocity-time graph.

A body moves with a velocity of $2 {\mathrm{ms}}^{-1}$ for $5 \mathrm{s}$. Then its velocity increases uniformly to $10 {\mathrm{ms}}^{-1}$ in next $5 \mathrm{s}$. Thereafter, its velocity begins to decrease at a uniform rate until it comes to rest after $10 \mathrm{s}$. Mark the portions of the graph to show when the motion of the body is uniform and when it is non-uniform on the velocity-time graph.

A body moves with a velocity of $2 {\mathrm{ms}}^{-1}$ for $5 \mathrm{s}$. Then its velocity increases uniformly to $10 {\mathrm{ms}}^{-1}$ in next $5 \mathrm{s}$. Thereafter, its velocity begins to decrease at a uniform rate until it comes to rest after $10 \mathrm{s}$. From the velocity-time graph, find the total distance moved by the body in initial $5 \mathrm{s}$ and initial $12 \mathrm{s}$ and in the last $10 \mathrm{s}$.

Discuss the graphs $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$ shown in the figure. Compare the total distance travelled and the displacements. Which portion of graph represents a motion in which displacement is zero?

A sprinter in a $100 \mathrm{m}$ race covers $4 \mathrm{m}$ in first second, $30 \mathrm{m}$ in next $4 \mathrm{s}$, $52 \mathrm{m}$ in another $4 \mathrm{s}$ and finishes the race in $10 \mathrm{s}$.

Calculate the average velocity of the sprinter. You may assume that during any given time interval the velocity is uniform.

A sprinter in a $100 \mathrm{m}$ race covers $4 \mathrm{m}$ in first second, $30 \mathrm{m}$ in next $4 \mathrm{s}$, $52 \mathrm{m}$ in another $4 \mathrm{s}$ and finishes the race in $10 \mathrm{s}$.

In which time interval, is the average velocity attained by the sprinter maximum? State this velocity in appropriate units.