- #1

songoku

- 2,340

- 340

- Homework Statement
- Figure below shows a light shelf supported by strut. The force by the strut is F, the force by the wall is R, and force by the books is W. Which diagram is correct?

- Relevant Equations
- Newton's Law

Judging from FBD of the shelf, the answer will be either (B) or (D) because there should be horizontal force to the left to balance the horizontal force to the right by F, and by considering the torque, I think the answer will be (B)

But I am confused about the direction of the normal contact force between the shelf and wall. If the direction of R is like in (B), then the direction of the normal contact force will be to the left. This means that the wall exerts force on the shelf to the left, not to the right? I thought the force by the wall on the shelf will always be to the right.

Thanks