Question

A box is lying on an inclined plane. If the box starts sliding when the angle of inclination is ${60}^o$, then find the coefficient of static friction of the box and plane.

• A. 2.732
• B. 1.732
• C. 0.267
• D. 0.176

Answer 1

Answer: (B)

1.732

Force along the surface (tangential component force ) = $mgsin{60}^0$
Normal component of force = $mgcos{60}^0$
$\therefore$ friction force = $\mu N$
= $\mu mgcos{60}^0$
Just before sliding
tangential component of for force = friction force
$mgsin60$ = $\mu mgcos{60}^0$
$\mu =\frac{mgsin{60}^0}{mgcos{60}^0}$
$=tan{60}^0$
$\mu =\sqrt{3}=1.732$