Calling all physics nerds! I am dumb as a box of rocks

[Col. Derontchi]

Alright folks. I am a true dummy when it comes to physics. I have a project that requires me to find the torque and all of the forces in the image below WITH inclusion of work in the final product and how I arrived there. I have all my forces labeled (I believe), however I have become stuck. Very stuck. Any help is greatly appreciated because this is due quite soon. Cheers!

Also, the guitar weighs 6.1 lbs. Pivot point and center of gravy are marked in green and blue.

Need to find:
- Force of gravity
- Both normal forces (must find torque first)
- All torques
  + includes moment arm, all that good stuff
- Tension force

[Ad Bot]

[Lego lad]

point of gravy

[Master Matthew²]

point of gravy

mmm....
gravy...

[Col. Derontchi]

point of gravy

fixed

[Lego lad]

center of gravy

[Col. Derontchi]

Can someone help me with the damn problem?

[AndroFox]

if you want to get actual help, you might want to make a proper illustration AND find a better place to ask

[bithead9]

I've taken a quick look at it, and I do not believe you can solve that knowing only the weight of the guitar. I set up a few equations, but I can't get around not knowing the angle that guitar makes with the ground (another way of putting it : the angle it makes with the force normal to the book) Also the diagram isn't clear, why is there a force of tension at the top?

[Juncoph]

I've taken a quick look at it, and I do not believe you can solve that knowing only the weight of the guitar. I set up a few equations, but I can't get around not knowing the angle that guitar makes with the ground (another way of putting it : the angle it makes with the force normal to the book)

measure the angle between the green line and the angle between the guitar and the green line, add the two angles, and use that for your angle. round it also

[Col. Derontchi]

if you want to get actual help, you might want to make a proper illustration AND find a better place to ask

it is proper. And I don't really have anywhere else. I've spent hours on this.

I've taken a quick look at it, and I do not believe you can solve that knowing only the weight of the guitar. I set up a few equations, but I can't get around not knowing the angle that guitar makes with the ground (another way of putting it : the angle it makes with the force normal to the book) Also the diagram isn't clear, why is there a force of tension at the top?

I've estimated the angle from the wall to be about 79 degrees. The ground is irrelevant. My teacher put that there when he was helping me out but it might have been torque. I don't remember which.

[bithead9]

it is proper. And I don't really have anywhere else. I've spent hours on this.I've estimated the angle from the wall to be about 79 degrees. The ground is irrelevant. My teacher put that there when he was helping me out but it might have been torque. I don't remember which.

I was just using the ground as a way to communicate a horizontal flat line.

These are the numbers I got, I'm not that confident in all of them, but I'll also give some work. (I didn't get to everything as I really need some sleep)

the force of gravity is 27.048N because I converted 6.1 pounds to kg and multiplied by 9.8
The net torque is of course 0 Nm, but I found that gravity and the normal force apply a torque of 104 Nm
(because the pivot location we can neglect the top forces) Therefore, Fg*r = Fn₁*r
We know Fg (27.048) and r is 29 inches (converted to meters, .7366m)/cos(79))
This means that the moment arm is 3.86m (this is where I'm unsure, I was never really good at torque)
Multiply those two numbers together to get ~104 Nm

I didn't get to the other normal force or the tension, but you know Fg and Fn₁ are the same value, and the sum of all the forces in the y direction are
Fg = Fn₂ + Tcos(79)
and in the x direction are
Fn₁ = Tsin(79)

Good luck, hopefully I'm not an idiot and made a ton of mistakes.

[Col. Derontchi]

I was just using the ground as a way to communicate a horizontal flat line.

These are the numbers I got, I'm not that confident in all of them, but I'll also give some work. (I didn't get to everything as I really need some sleep)

the force of gravity is 27.048N because I converted 6.1 pounds to kg and multiplied by 9.8
The net torque is of course 0 Nm, but I found that gravity and the normal force apply a torque of 104 Nm
(because the pivot location we can neglect the top forces) Therefore, Fg*r = Fn₁*r
We know Fg (27.048) and r is 29 inches (converted to meters, .7366m)/cos(79))
This means that the moment arm is 3.86m (this is where I'm unsure, I was never really good at torque)
Multiply those two numbers together to get ~104 Nm

I didn't get to the other normal force or the tension, but you know Fg and Fn₁ are the same value, and the sum of all the forces in the y direction are
Fg = Fn₂ + Tcos(79)
and in the x direction are
Fn₁ = Tsin(79)

Good luck, hopefully I'm not an idiot and made a ton of mistakes.

Everything looks good to me. I don't really remember torque so I don't know though. I really appreciate it either way.

If anyone else would like to evaluate it, that's fine too.