Wall supporting force (upward): This is the force that opposes the gravitational force and keeps the picture frame from falling. It is provided by the wall on which the frame is mounted. The strength of this force depends on the nature of the wall and how securely the picture frame is attached.
Tension in hanging wire (upward): If a picture frame is using a hanging wire, this wire provides some or all of the upward force to support the frame. The tighter the wire, the greater the tension and thus more of the picture frame's weight is being held up.
Friction (horizontal): This is the force between the picture frame and the wall, opposing any horizontal movement. It is influenced by the surface roughness and the nature of the contact between the wall and the picture.
