The direction of acceleration of an object moving in a circular path is

Name the force which is responsible for change in position or state of an object.

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.

$(a)$ Which type of motion is represented by the velocity-time graph shown below?
$(b)$ Name the physical quantity which can be calculated by the area of rectangle $OABC$.
$(c)$ What does the straight line $AB$ represent?

$(a)$ Define uniform circular motion.
$(b)$ Ram goes for a morning walk in a circular park daily. He completes one revolution of the park in $4$ minutes. Find his speed if the diameter of the park is $420\, m$.
$(c)$ Draw velocity$-$time graph for uniform motion along a straight line. How can you find the distance covered by a body from this graph?

Mention some uses of velocity-time graphs.