Question

A block of mass $mkg$ is sliding from rest on an inclined rough surface of inclination $\theta$ as shown in the figure under the action of three forces, weight normal and frictional force only. The magnitude of force are $20N,40N$ and $50N$ not necessarily in the same order. The value of $g$ is $10{m/s}^2$. Now match the physical quantity in $List-I$ with their magnitude in $List-II$ in $SI$ unit and select the correct answer using the codes given below the lists: (assume that the coefficient of kinetic friction is less than $1$).

Answer 1

$N=mg\cos \theta =50\times \frac{4}{5}=40N$
$f_X=\mu mg\cos \theta =0.5\times 50\times \frac{4}{5}=20N$
$mg\sin \theta =50\times \frac{3}{5}=30N$
$a=\frac{30-20}{5}=2{m/s}^2$
$\therefore A-2$
$B-1$
$C-3$
$D-2$