Solve Broken Leg & Pulleys: Find Weight W

  • Thread starter Thread starter stunner5000pt
  • Start date Start date
  • Tags Tags
    Broken Pulleys
AI Thread Summary
The discussion revolves around solving for the weight W attached to a pulley system, given a total downward force of 38N exerted by the leg. Various equations are presented to analyze forces in both the X and Y directions at different points in the system, with a focus on tension (T) and its relationship to the forces involved. A participant questions the approach, suggesting that breaking forces into components may not be necessary and highlights a missing tension force in the equations. The conversation emphasizes the need for clarity in force diagrams and the correct application of equilibrium principles. The overall goal is to confirm the accuracy of the equations and determine the value of T.
stunner5000pt
Messages
1,443
Reaction score
4

Homework Statement


assume that the total downward force exerted at A & B by the leg is 38N. find the weight W, attached on the lower puller

Homework Equations


please see attached diagram

The Attempt at a Solution


[/B]
i have written roman numerals to help determine which equation refers to which point

at point I
W = Tat point II
in the X direction
T \cos 25 + F_{1} = F_{A} cos \theta
in the y direction

T \sin 25 = F_{A} \sin \theta

at point III
in the X direction
0=T \cos 20 +T \cos 25

in the Y direction

T \sin 20 + T \sin 25

at point IV

in the X direction

T \cos 20 + T \cos 60 = 0in the Y direction

-T \sin 20 - T\sin 60 = 0

And that the end of this, can we say that T = 38N?

Please let me know if all the equations are correct?
Thank you for your input and assistance!
 

Attachments

  • leg question.jpg
    leg question.jpg
    23.6 KB · Views: 501
Physics news on Phys.org
stunner5000pt said:

Homework Statement


assume that the total downward force exerted at A & B by the leg is 38N. find the weight W, attached on the lower puller

Homework Equations


please see attached diagram

The Attempt at a Solution


[/B]
i have written roman numerals to help determine which equation refers to which point

at point I
W = Tat point II
in the X direction
T \cos 25 + F_{1} = F_{A} cos \theta
in the y direction

T \sin 25 = F_{A} \sin \theta

at point III
in the X direction
0=T \cos 20 +T \cos 25

in the Y direction

T \sin 20 + T \sin 25

at point IV

in the X direction

T \cos 20 + T \cos 60 = 0in the Y direction

-T \sin 20 - T\sin 60 = 0

And that the end of this, can we say that T = 38N?

Please let me know if all the equations are correct?
Thank you for your input and assistance!
Well I'm not sure of this problem but if the lower leg is horizontal and takes only an axial pulling force F1 , then draw the FBD of the pulley at the foot and sum vertical forces to solve for T and thence mg. F-a is given I think as a vert force of 38 N at A so I don't know why you are breaking it into components. You are also missing a tension force in your equation at that pulley.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top