Question

A body takes just twice the time as long to slide down a plane inclined at 30^o to the horizontal as if the plane were frictionless. The coefficient of friction between the body and the plane is

• A. $\frac{\sqrt{3}}{4}$
• B. $\sqrt{3}$
• C. $\frac{4}{3}$
• D. $\frac{3}{4}$

Answer 1

Answer: (A)

$\frac{\sqrt{3}}{4}$

Answer 2

$\mu = \tan\theta\left( 1 - \frac{1}{n^{2}} \right) = \tan 30\left( 1 - \frac{1}{2^{2}} \right) = \frac{\sqrt{3}}{4}$.