Question

A wheel of moment of inertia 2 kg m² is rotating at a speed of 25 rad/s. Due to friction on the axis, it comes to rest in 10 minutes. Total work done by friction is ______.

Options

• 25 J

• 625 J

• 50 J

• 600 J

Answer 1

A wheel of moment of inertia 2 kg m² is rotating at a speed of 25 rad/s. Due to friction on the axis, it comes to rest in 10 minutes. Total work done by friction is 625 J.

Explanation:

W = τθ = I α θ = 2αθ

`omega_2^2 = omega_1^2 - 2 alpha theta`

0 = (25)² - 2 α θ

∴ 2 α θ = 625

∴ W = 625 J