# How is this system in equilibrium?

[diagram attached]

Assume some friction between M and the surface.

The forces acting on the connector point are the forces of friction of the M blocks and the weight of m, but they are in different directions; how do they manage to cancel out?

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CWatters
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By being in opposite directions.

Aside: If the string (?) joining the blocks really was horizontal the tension would be infinite so it must sag a bit. Assume it sags to an angle θ with the horizontal. Then look at the horizontal and vertical components. The vertical components adds to the normal force on the blocks. The horizontal force is opposed by friction etc.

Last edited:
But the weight of m is perpendicular to the frictional forces

CWatters
Homework Helper
Gold Member
But the weight of m is perpendicular to the frictional forces
There are other vertical forces.

See my earlier reply that I edited.

CWatters
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Can I check the line joining the blocks is indeed something like string and not a rigid rod?

Yes. Sorry I thought that was implied.

Ah, I see now. It is physically impossible for the strings to be 100% perpendicular, correct?

CWatters