A gramophone record takes 5s to reach its constant angular velocity of 4π rads‾¹ from rest. Find its constant angular acceleration.

A. 0.4π rads‾²
B. 0.8π rads‾²
C. 1.3π rads‾²
D. 20.0π rads‾²

Correct Answer:

Option B = 0.8π rads‾²

Explanation

From the radiation:
V = +at, and if it starts from N & T, U = 0
And for angular motion, W = O + at
4R = aχ5
∴ a = (4a)/5 = 0. 8π rads‾²