11. A uniform sign is supported against a wall at point P as shown in the figure. If the sign is a square 0.4 m on a side and its mass is 4.0 kg, what is the magnitude of the horizontal force that the wall at P experiences?
(A) 5.8 N
(B) 10.0 N
(C) 20 N
(D) 98 N
(E) 75 N.
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統計: A(1), B(1), C(12), D(0), E(0) #3093852
統計: A(1), B(1), C(12), D(0), E(0) #3093852