Question

All surfaces shown in the figure are frictionless. A block of mass $2kg$ is kept on a wedge of mass $10kg$. If the mass $m$ remains stationary w.r.t wedge, the magnitude of force $P$ is: ($g=10m/s^2$)

• A. $15N$
• B. $90N$
• C. $12N$
• D. $45N$

Answer 1

The correct option is B $90N$

Let the acceleration of system is a

$P=(M+m)a$

$=12a$

F.B.D of block w.r.t wedge is

Balancing the force

$masin53=mgsin37$

$N=mgcos37+macos53$

$a=10\ast \frac{3}{5}\ast \frac{5}{4}$

$=7.5m/s^2$

$F=12\ast 7.5$

$=90N$