Can a particle be accelerated
$(i)$ if its speed is constant?
$(ii)$ if its velocity is constant?

Four speed-time graphs are shown below. Which graph represents the following cases?
$(i)$ $A$ ball thrown vertically upwards and returning to the hand of the thrower.
$(ii)$ $A$ body decelerating to a constant speed and then accelerating.

$A$ stone is thrown vertically upward with an initial velocity of $40 \, m/s$. Taking $g = 10 \, m/s^2$,find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?

Answer the following questions:
$(i)$ State the type of motion shown by a freely falling stone.
$(ii)$ When a stone is thrown vertically upwards,its velocity is continuously decreased. Why?
$(iii)$ Give an example of a motion in which average velocity is zero,but the average speed is not zero.

An object starts a linear motion with velocity $u$ and with uniform acceleration $a$,it acquires a velocity $v$ in time $t$.
$(a)$ Draw its velocity-time graph.
$(b)$ Obtain the first equation of motion,$v = u + at$,for the velocity-time relation by using the velocity-time graph.
$(c)$ $A$ body moving with a velocity of $2 \, m s^{-1}$ acquires a velocity of $10 \, m s^{-1}$ in $5 \, s$. Find its acceleration.

The speed-time graphs of two cars are represented by $P$ and $Q$ as shown below.
$(a)$ Find the difference in the distance travelled by the two cars (in $m$) after $4\, s$.
$(b)$ Do they ever move with the same speed? If so,when?
$(c)$ What type of motion are car $P$ and car $Q$ undergoing?