Question

Find the minimum force P required to move block of weight W up the incline plane

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

Since we have to just move the block up the inclined so the friction will be downward and limiting.

$\Rightarrow N+Psin\alpha =mgcos\lambda$

N = $mgcos\alpha -Psin\alpha$ ........(I)

$P\cos \alpha =mg\sin \lambda +fr$

$P\cos \alpha =mg\sin \lambda +\mu N$

$P\cos \alpha =mg\sin \lambda +\mu (mg\cos \lambda -P\sin \alpha )$

$P(\cos \alpha +\mu \sin \alpha )=mg\sin \lambda +\mu mg\cos \lambda$

$P=mg\frac{\sin \lambda +\mu \cos \lambda }{\cos \alpha +\mu \sin \alpha }$