Question

A block of mass "$5kg$" is placed on a wedge having inclination of $37^{\circ }$ with the horizontal. Coefficient of friction between block and wedge is $0.8$. Then select the correct statement:

• A. Friction force between block and the wedge is 32 N.
• B. Friction force between block and the wedge is 30 N.
• C. Contact force between block and wedge is 80 N.
• D. Contact force between block and wedge is 40 N.

Answer 1

Answer: (B)

$f_{\max }=\mu mg\cos \theta$
$=.8\times 5\times 10\times \frac{4}{5}=32$
as $f_{\max }>mg\sin \theta$ hence
friction $=mg\sin \theta$
$=5\times 10\times \frac{3}{5}=30$ Newton
and $N=mg\cos \theta =40N$
$\Rightarrow$ Contact force $=\sqrt{(30{)}^2+(40{)}^2}=50N$