Check my static equilibrium diagrams

In summary, the physics fan's diagrams are confusing to the professor and he needs to add individual force vectors to the weights and show the mass and location of the ruler independently from the weights to make sure the equilibrium condition is depicted correctly.
  • #1
bananan
176
0
Hi physics fans,

I've made four diagrams for inclusion in a physics lab report. They depict situations in which a meter stick is in static equilibrium (no net torque, no net force). My professor mentioned to me that my analysis of the forces on the stick is not correct, but was not more specific than that.

Can you take a look at my diagrams and help me figure out where my error is? Do I need to show a force vector pointing towards the Earth for each weight attached to the meter stick? I thought it was correct to consolidate all of them into one (since the center of mass of the system has to be over the pivot point for static equilibrium to exist) Links to my diagrams are below:

http://img325.imageshack.us/img325/9105/physlab8apparatus1sn5.th.png
http://img261.imageshack.us/img261/3782/physlab8apparatus2fk8.th.png
 
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  • #2
To me, the diagrams are confusing for the reason you stated.

"Do I need to show a force vector pointing towards the Earth for each weight attached to the meter stick?"

So, yes. The diagrams look easy on the eyes, but is the professor looking for more of a plain free body diagram?

Maybe add to the pivot point that sum of the moments about the pivot point is equal to zero. EMpivot=0
 
Last edited:
  • #3
Well, the trouble with plain free body diagrams is that they don't show both torques and forces. I think the professor is ok with the format of the diagrams, but your advice about adding individual force vectors to the weights is well taken.

One other question: in diagram four, does there need to be a torque vector pointing "out of the page" on the left side of the pivot point? I believe I need to add this, since (W-left side of ruler) * (moment arm from pivot to left side of ruler center of mass) is > 0.
 
  • #4
I would also show the mass and location of the ruler independently from the weights because a condition of equilibium cannot be seen as depicted.
 

Related to Check my static equilibrium diagrams

1. What is a static equilibrium diagram?

A static equilibrium diagram is a graphical representation of the forces acting on an object that is at rest. It shows the magnitude and direction of each force, as well as the object's position and orientation.

2. Why is it important to check my static equilibrium diagrams?

Checking your static equilibrium diagrams is important because it allows you to ensure that all the forces acting on an object are balanced, which is necessary for the object to remain at rest. It also helps you identify any errors or inconsistencies in your calculations.

3. How do I know if my static equilibrium diagram is correct?

To determine if your static equilibrium diagram is correct, you can use the laws of static equilibrium, which state that the sum of all forces acting on an object must be equal to zero and the sum of all torques must also be equal to zero. If these conditions are met, your diagram is considered correct.

4. What are the key components of a static equilibrium diagram?

A static equilibrium diagram typically includes the object being analyzed, the forces acting on the object, and the direction and magnitude of each force. It also includes the position and orientation of the object, as well as any known dimensions or angles.

5. How can I improve my understanding of static equilibrium diagrams?

To improve your understanding of static equilibrium diagrams, it is important to practice solving problems and drawing diagrams for different scenarios. You can also seek help from a teacher or tutor, or consult online resources and textbooks for additional explanations and examples.

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