Question

Angle $\theta$ shown in graph between friction and applied force on a body is :

• A. ${60}^{\circ }$
• B. ${45}^{\circ }$
• C. ${30}^{\circ }$
• D. ${25}^{\circ }$

Answer 1

The correct option is B ${45}^{\circ }$


In $\Delta OAB,\tan \theta =\frac{f_o}{F_o}$ ... (1)
At point $A$, friction force on body is static and we know, in static state, magnitude of applied force is equal to frictional force.
$\therefore F_o=f_o$
$\Rightarrow \tan \theta =1$ [from (1)]
$\Rightarrow \theta ={45}^{\circ }$
Angle between friction and applied force in static state is ${45}^{\circ }$