Static equilibrium problem -- with a pulley

In summary: I think i got it fixed.In summary, the student attempted to solve a homework problem but did not appear to have fully understood the terms and calculations involved.
  • #1
J-dizzal
394
6

Homework Statement


20150718_174005_zpspkrqlnql.jpg


Homework Equations


sum of forces equal to zero.

The Attempt at a Solution


20150718_200836_zpsvjmoossd.jpg
 
Last edited:
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  • #2
Looks like you left out a moment arm in one of your terms in ΣMA.
 
  • #3
I can't really follow your work computing components of forces and making sure each force contributes to torque.
 
  • #4
Thank you, i didnt notice the 6in on the pulley at first.
TSny said:
Looks like you left out a moment arm in one of your terms in ΣMA.

Dr. Courtney said:
I can't really follow your work computing components of forces and making sure each force contributes to torque.
I updated my original post but I am still getting the same answer haha.
 
  • #5
Note that FDBsinθ is a force component, not a moment. What's the moment arm for this force?
 
  • #6
TSny said:
Note that FDBsinθ is a force component, not a moment. What's the moment arm for this force?
oh crap sorry, let me finish that equation.
Ok, for the sum of moments i got 830.5 lb, now let me correct the rest of the equations and see what i get for an answer to the magnitude of A.
edit. 880.7 lb
edit2. 1761.5
 
Last edited:
  • #7
In the ΣMA equation, your last term is -FDB. Is this meant to be there?
 
  • #8
TSny said:
In the ΣMA equation, your last term is -FDB. Is this meant to be there?
no its not supposed to be there, I've change it again, I've edited my original post. there is still something wrong with it though...
 
  • #9
Check your calculation of Ax. Looks like you have it set up correctly, but made some sort of mistake in plugging the numbers in your calculator.
 
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  • #10
TSny said:
Check your calculation of Ax. Looks like you have it set up correctly, but made some sort of mistake in plugging the numbers in your calculator.
thanks.
I got a new HP 300s calculator in the mail today, still getting used to it...
 

1. What is the definition of static equilibrium?

Static equilibrium refers to a state in which all forces and torques acting on an object are balanced, causing the object to remain at rest or in a constant state of motion.

2. How does a pulley affect the static equilibrium of a system?

A pulley is a simple machine that can change the direction of a force and distribute it evenly across multiple objects. In a static equilibrium problem, a pulley can help balance out forces and keep the system stable.

3. What are the key principles to consider when solving a static equilibrium problem with a pulley?

When solving a static equilibrium problem with a pulley, it is important to consider the forces acting on the pulley, both in terms of magnitude and direction. The tension in the rope and the weight of the objects on either side of the pulley must also be taken into account.

4. How can you determine the tension in a rope in a static equilibrium problem with a pulley?

The tension in a rope can be determined by using the principle of conservation of energy and/or the principle of moments. These principles allow you to calculate the unknown forces and torques in the system and determine the tension in the rope.

5. What is the significance of solving a static equilibrium problem with a pulley?

Solving a static equilibrium problem with a pulley can help you understand the forces and torques acting on a system and how they are balanced. This can be applied to real-world situations, such as designing structures or machines, to ensure they are stable and can withstand different forces.

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