Question

Please tell me that for rotational motion, pivoted point is needed..no/ yes then why justify?

Answer 1

An angle is just a way to measure how much exactly an object has spun, or how far around the circle an object has gotten. Of course, we could also measure the distance around the circle in terms of position (say, along the circumference), but angle is a very convenient shorthand, and handy if we're more concerned about the details of the rotation than the translation. Hint: in this chapter, we're more concerned with rotation than translation.