State the meaning of uniform circular motion.

State whether the following statement is true or false:
$A$ quantity which can be completely specified by magnitude as well as direction is called a scalar quantity.

$A$ person is running along a circular path in a park.
$(a)$ At what point does he change his direction while running?
$(b)$ If he covers half of the circular path,what will be his displacement? Draw a diagram showing it.

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.

Starting from rest,a scooter acquires a velocity of $36 \, km/h$ in $10 \, s$ and then brakes are applied,taking $20 \, s$ to stop. Calculate the acceleration and the total distance travelled.

$A$ circular cycle track has a circumference of $314 \ m$ with $AB$ as one of its diameters. $A$ cyclist travels from $A$ to $B$ along the circular path with a velocity of constant magnitude $15.7 \ m s^{-1}$. Find the:
$(a)$ distance moved by the cyclist.
$(b)$ displacement of the cyclist,if $AB$ represents the north-south direction.
$(c)$ the average velocity of the cyclist.