Acceleration Of Block Against Friction MCQ - Practice Questions with Answers

• Case 1:- Acceleration of a block on a horizontal surface

• When the body is moving under application of force P, then kinetic friction opposes its motion.

              Let a is the net acceleration of the body.

           From the figure,

               ma = P - F_K

        $a=\frac{P-F_K}{m}$

• Case 2:- Acceleration of a block sliding down over a rough inclined plane

• When the angle of the inclined plane is more than the angle of repose, the body placed on the inclined plane slides down with an acceleration a.

               From the figure,

$\begin{aligned} & m a=m g \sin \theta-F \\ & m a=m g \sin \theta-\mu R \\ & m a=m g \sin \theta-\mu m g \cos \theta \\ & a=[\sin \theta-\mu \cos \theta] \\ & \text { For } \mu=0 \quad \therefore \quad a=g \sin \theta\end{aligned}$

• Case 3:- Retardation of a block sliding up over a rough inclined plane

• When the angle of the inclined plane is less than the angle of repose, then for the upward motion

$\begin{aligned} & m a=m g \sin \theta+F \\ & m a=m g \sin \theta+\mu m g \cos \theta \\ & m a=g[\sin \theta+\mu \cos \theta] \\ & a=g[\sin \theta+\mu \cos \theta] \\ & \text { For } \mu=0 \\ & a=g \sin \theta\end{aligned}$