When a picture is hung on a smooth vertical wall using a wire and a nail, as in Figure, the picture almost always tips slightly forward, i.e., the plane of the picture makes a small angle with the vertical.

(a) Explain why pictures supported in this manner generally do not hang flush against the wall.

(b) A framed picture 1.5 m wide and 1.2 m high and having a mass of 8.0 kg is hung as in Figure using a wire of 1.7 m length. The ends of the wire are fastened to the sides of the frame at the rear and 0.4 m below the top. When the picture is hung, the angle between the plane of the frame and the wall is 5.0^o. Determine the force that the wall exerts on the bottom of the frame.