A weight $W$ can be just supported on a rough inclined place by a force $F$ either acting along the plane or horizontally. If $\theta$ is the angle of friction, then $\mathrm{F} / \mathrm{W}$ is

• Correct answer
  A

  $\tan \theta$
• B

  $\sec \theta$
• C

  $\sin \theta$
• D

  $\cos \theta$

Solution

Angle of friction, is the angle which the resultant of limiting friction and normal reaction makes with the normal reaction.
$\therefore$ $$ \tan \theta=\frac{F}{R} $$ Or $$ \frac{F}{W}=\tan \theta $$

Hence, the correct answer is option: 'A'.