Question

A disc revolves in a horizontal plane at a steady rate of 3 rad/s. A coin will remain on the disc if kept at a distance of 20 cm from the axis of rotation. The coefficient of friction is: (g= 10 m $s^{-2}$)

• A. 0.5
• B. 0.3
• C. 0.18
• D. 0.72

Answer 1

The correct option is C 0.18

$m{\omega }^{2}r=fm{\omega }^{2}r=\mu mg9\times \frac{{20}^2}{100}=\mu \times 10\mu =0.18$