A plank attached to the wall and F exerted by wall

[AmirTimur]

---

Members do not see this ad.

Can someone please explain this concept to me? Whenever problems involve a plank attached to the wall (horizontal to floor let's assume), then the wall exerts a force on a plank. This force has a horizontal x components (parallel to plank) and a vertical y component (parallel to wall). Vertical component points up, and vertical components points in the direction of the plank's other end (it points also parallel to the plank).

Now, I can just accept that this is the way it is. But would anyone have a qualitative explanation for why the force exerted by wall on the plank they way it is? Why is it that the components point the way they do? Please HELP!

 

[sc4s2cg]

I'm not sure what you're scenario looks like. Mind drawing it out on paint? 🙂

 

[AmirTimur]

I'm not sure what you're scenario looks like. Mind drawing it out on paint? 🙂

Thanks for the reply. I attached the pic. Another opportunity to show off my "awesome" paint skilzzz

 

[PinknGreenMD]

because of gravity. F(g) .. draw out your triangles and your angles and insert your force of gravity formulas then you can put a number to each force and the torques.

 

[Testosterone]

Assuming your diagram is in translational equilibrium then the sum of all forces must equal zero. There is a vertical gravitational force pointing downwards which must be balanced out by a support force from the hinge in order to keep the net vertical force zero. There are no horizontal forces acting on the system so the horizontal support force is zero.

One way to intuitively think about this is that without the supporting force from the hinge, the system will not be in equilibrium, there will be a nonzero net force leading to acceleration, leading to motion (the plank will drop).