But you can also be lazy. For example, there is no mention of friction between m and m in the title. . Then suppose that wood has friction. Suppose the included angle of the inclined plane is a.
There is ma=mgsinA for m, so the pressure of m on m is mgcosA.
At this time, the force analysis of m is carried out. M is subjected to its own gravity, the pressure from M, the supporting force from the ground N, and a ground friction force that does not know the direction.
Because the pressure from m is perpendicular to the inclined plane, there is a horizontal component to the right. In order to make the slope static, a horizontal left F must be applied to the ground.
And because the pressure of m to m is mgcosA, the vertical component of the pressure is that mgcosA cosA is less than mg. . . Therefore, the support degree of n to m is also less than (m+m+m) g g.
In fact, even if there is friction between m and m, it can be calculated that the horizontal component of M-M pressure is greater than the horizontal component of M-M friction ~ ~
For such a topic, first find a simple part and analyze it independently. You will know ~