$(a)$ 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?

(N/A) body is said to be in uniform circular motion if it moves along a circular path with a constant speed.
$(b)$ Given:
Time $(t) = 4 \text{ minutes} = 4 \times 60 = 240 \text{ s}$
Diameter $(d) = 420 \text{ m}$
Radius $(r) = d / 2 = 420 / 2 = 210 \text{ m}$
Total distance $(S)$ covered in one revolution $= 2 \pi r = 2 \times (22 / 7) \times 210 = 1320 \text{ m}$
Speed $(v) = \text{Distance} / \text{Time} = 1320 / 240 = 5.5 \text{ m s}^{-1}$
$(c)$ The velocity$-$time graph for uniform motion along a straight line is a straight line parallel to the time axis. The area under the velocity$-$time graph gives the distance covered by an object.