Pulley System equilibrium problem

In summary: I was thinking of the component-wise sums of forces. The Fx and Fy sums need to each sum to zero, right? That should be how you can work out the final tensions, especially for mass M.
  • #1
Dcarroll
7
0

Homework Statement



If the system below is in equilibrium, show that tan(Theta) = 1 + (2M/m)

View attachment Doc1.doc

Homework Equations



F=ma

The Attempt at a Solution



I was pretty confused with this problem. All I think I know is that the force being pulled downward on M is F=mg/2. Can someone explain to me how to solve the next part?
 
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  • #2
Dcarroll said:

Homework Statement



If the system below is in equilibrium, show that tan(Theta) = 1 + (2M/m)

View attachment 29838

Homework Equations



F=ma

The Attempt at a Solution



I was pretty confused with this problem. All I think I know is that the force being pulled downward on M is F=mg/2. Can someone explain to me how to solve the next part?

Can you post your Free Body Diagram (FBD) sketches of the two masses for this problem? That's usually a good first step in this type of problem.
 
  • #3
Ok I tried drawing the free body diagrams for the masses-

View attachment Doc1.doc
 
  • #4
Dcarroll said:
Ok I tried drawing the free body diagrams for the masses-

View attachment 29854

That's a start. I don't think you can write the upper right vector on M just yet, though. Now, for each FBD, what equations do you write, and how do you use them to solve for the tensions?
 
  • #5
Well don't I have the equations in my FBD? For example the tension force caused by "m" is F=mg, and the two tensions for the strings holding "m" up are F=mg/2? I am just confused on what to do next. We have never done any problems like this
 
  • #6
Dcarroll said:
Well don't I have the equations in my FBD? For example the tension force caused by "m" is F=mg, and the two tensions for the strings holding "m" up are F=mg/2? I am just confused on what to do next. We have never done any problems like this

I was thinking of the component-wise sums of forces. The Fx and Fy sums need to each sum to zero, right? That should be how you can work out the final tensions, especially for mass M.
 

FAQ: Pulley System equilibrium problem

What is a pulley system equilibrium problem?

A pulley system equilibrium problem is a physics problem that involves calculating the forces and tensions acting on a system of connected pulleys in order to determine the system's equilibrium state.

How do you solve a pulley system equilibrium problem?

To solve a pulley system equilibrium problem, you first need to identify all the forces acting on the system, including the weight of the objects and the tensions in the ropes. Then, you can use the principles of equilibrium to set up and solve equations that will determine the unknown forces and tensions.

What are the key principles of equilibrium in pulley systems?

The key principles of equilibrium in pulley systems include the fact that the sum of all forces acting on the system must equal zero, and that the sum of all moments (torques) acting on the system must also equal zero. Additionally, the tension in a rope passing over a pulley is equal on both sides of the pulley.

What are some common mistakes when solving pulley system equilibrium problems?

Some common mistakes when solving pulley system equilibrium problems include forgetting to include all forces in the system, incorrectly setting up equations, and failing to account for the direction of forces and tensions. It is also important to carefully label all forces and to use the correct units in calculations.

How does friction affect pulley system equilibrium problems?

Friction can affect pulley system equilibrium problems by adding an additional force that must be accounted for in calculations. In some cases, friction may prevent a system from reaching equilibrium, and the amount of friction must be carefully considered in order to accurately solve the problem.

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