A sign is supported at its top right corner, point P. The sign is a square with 40 cm on each side and has 8.0 kg mass. What is the magnitude of the horizontal force that P experiences?

Answer 1

If the sign is supported only at P, it requires a moment connection and there is no horizontal force.

Assume that the sign is supported at P and the bottom of the same side (40 cm down) is butted against the support.

Take moments:
mg * (40/2) = P*40

Solve for P.

Answer 2

Where did the 40/2 come from?

Answer 3

40/2 Came from Steve's answer, get with it.