# What are the physics behind a TV wall mount?

As I was installing this wall mount, I began to wonder how exactly physics is at work with it. In other words, how does the design of the mount play a role in ensuring that the mount itself supports the television/device and distributes the forces at play? I have seen different types of wall mounts (like this). Does the shape or structure of the mount make one much stronger (more efficient at distributing the forces) than another? Outside of allowing rotation does the swivel extension make the mount any better withstanding the forces?

I initially asked this question here on the Physics Stack Exchange but I think it is more suited for this platform. I came across this answer and this question as well. Thank you.

• Forces, moments and levers. All good search terms for this. Apr 18, 2022 at 19:47
• This is an interesting problem that involves many factors - the material of the wall, the inserts in the wall, the length of the cantilevered structure, the material of the cantilevered structure etc. A back-of-the-envelope calculation would find the maximum forces and moments in a simplified version (a simple beam, for example) and compute the stresses and deflections of the structure and the wall attachments. Comparison with the allowable stresses for the materials involved would tell you whether everything will be stable. Drywall attachments are usually the biggest problem. Apr 18, 2022 at 20:12
• @SolarMike Thank you for that. Apr 19, 2022 at 5:30
• @BiswajitBanerjee Wow, thank you for that. When I came across the mount my curiosity began to spew over. As I began to research I wasn't able to come up with the right terminology to really hit the nail on the head. You laid a great foundation for me to build upon. Once again thank you. Apr 19, 2022 at 5:40

Addressing the most basic but severe conditions we leave alone all the secondary connections, forces, and moments! Let's assume:

• P= the weight of the TV
• L= the length of each one of the two brackets
• H= the height of the brackets
• D= the distance between the two screws fastening the bracket to the wall's 2x4s or load-worthy material.

The highest pullout stress on the fasteners is when the bracket is stretched at 90 degrees to the wall acting as a cantilever beam.

$$T=C=\frac{2L*P}{D}$$ Half this stress is applied at the hinge between the two sub brackets.

The maximum torque is when the bracket is fully extended but almost touching the wall (to pan the TV! say.). there will be a sheer force on the screws trying to rotate them off the wall.

$$\tau= \frac{2LP}{D}$$

Intermediary torque is when the bracket is deployed in an L shape, the sub bracket coming out of the wall the second sub bracket turned 90 degrees.

$$\tau=\frac{PL}{D}$$ And the forces on the hinges are a combination of compression $$\ C=T=PL$$ and tension and also shear due to torque $$\ \tau= \frac{PL}{H}$$.

In between angles will have the $$sin(\theta)PL$$ and $$cos(\theta)PL$$ components.

• First, thank you for the response. The geek in me is going crazy lol. The formulas help me to see and have a better understanding of "why". I have a question though, why is the weight of the TV doubled within the formula (2P)? Apr 19, 2022 at 6:29
• @יהודה I should have put it 2LP to make it read better., the moment arm is 2L! The load is not multiplied. the sub-bracket length, L is multiplied. i edited the answer. Apr 19, 2022 at 6:35
• Ahh, that makes a lot more sense. Thank you for the correction and clarification, Mr. Kamran. Apr 19, 2022 at 17:00