Question

A cube of 10 N rests on rough inclined plane of slope 3 in 5. The coefficient of friction is 0.6. The minimum force necessary to start the cube moving up the plane is

• A. 8.8 N
• B. 16.2 N
• C. 10.8 N
• D. 21.6 N

Answer 1

The correct option is C 10.8 N

Slope 3 in 5 means 3 vertical distance in 5 horizontal motion:
$F=\left(mg\right)\sin \theta +{\mu }_k$ mg $\cos \theta$
$\theta =si{n}^{-1}\left(3/5\right);\mu =0.6;mg=10N$

$F=mgsin\theta +\mu mgcos\theta =10.8$