Can the speed of a body be negative?

Draw velocity-time graphs for the following situations:
$(i)$ When a body is moving with uniform velocity.
$(ii)$ When a body is moving with variable velocity,but uniform acceleration.
$(iii)$ When a body is moving with variable velocity,but uniform retardation.
$(iv)$ When a body is moving with variable velocity and variable acceleration.

$A$ cyclist goes once around a circular track of diameter $105 \, m$ in $5 \, minutes$. Calculate his speed. (in $m/s$)

State which of the following situations are possible and give an example of each of these:
$(a)$ $A$ body moving with constant acceleration but with zero velocity.
$(b)$ $A$ body moving horizontally with an acceleration in the vertical direction.
$(c)$ $A$ body moving with a constant speed in an accelerated motion.

An athlete completes one round of a circular track of diameter $49 \,m$ in $20 \,s$. Calculate the distance covered and displacement at the end of $30 \,s$.

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