Solving Pulley Problem: Find T1, T2, W1, W2, Alpha

  • Thread starter ana111790
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In summary: Also, remember that the tension in the cable is the same for both pulleys.In summary, to find T1, T2, W1, W2, and the angle Alpha for the leg to stay in equilibrium, you will need to use 5 equations: the sum of Fy and Fx equations for each pulley and the sum of moments around points A, B, and C. Remember to use Newton's 3rd law and that the tension in the cable is the same for both pulleys.
  • #1
ana111790
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Homework Statement


A patient's leg is held in position by 2 weights tht are connected through cables. The weight of the leg is W = 300N. L is the horizontal distance between the points where the cables connect with the leg (points A and B) and C is the center of gravity for the leg, located 2/3 L away from A. The angles from cable 2 is Beta=45 degrees.
Find T1, T2, W1, W2, and the angle Alpha for the leg to stay in equilibrium.
[PLAIN]http://img820.imageshack.us/img820/2055/drawing5.jpg


Homework Equations


Sum of Fy=0
Sum of Fx=0
Sum of Moments = 0

The Attempt at a Solution



So I separated the pulleys, so have for the weight and pulleys on left:
Sum of Fy= T1-W1=0
For the weight and pulleys on right:
Sum of Fy=T2-W2=0 (is this correct? What is the effect of the second pulley on the tension?)

Sum of Fy= T1sin(Alpha) - W +T2sin(45)
(Should these be T1sin and T2 sin or just T1 and T 2?)

Then I did sum of moments:
Sum of moments around point A = -W*2L/3 + T2sin(45)*L=0
Sum of moments around C = -T1sin(Alpha)*2L/3 + T2sin(45)*L/3
Sum of moments around B = W*L/3 + T1sin(Alpha)*L

So basically I'm stuck. Not sure if so far it's correct of how to proceed.
 
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  • #2
Can anyone help me out? Please.
 
  • #3
You have 5 unknowns so you will need 5 equations. Your moments all look okay to me, but your forces need some revision. You need to revise your Fy equation, and create an equation for Fx. Remember to use Newton's 3rd law to work out any kinks.
 

Related to Solving Pulley Problem: Find T1, T2, W1, W2, Alpha

1. What is a pulley?

A pulley is a simple machine consisting of a wheel with a grooved rim and a rope or chain wrapped around it. It is used to change the direction of a force or to lift objects.

2. How do you solve a pulley problem?

To solve a pulley problem, you need to understand the concept of mechanical advantage and the relationship between tension, weight, and acceleration. You also need to use Newton's laws of motion and the equations of rotational motion.

3. What are T1, T2, W1, W2, and Alpha in a pulley problem?

T1 and T2 are the tensions in the two segments of rope or chain that support the pulley. W1 and W2 are the weights of the objects being lifted or moved by the pulley. Alpha is the angle of rotation of the pulley.

4. How do you find T1, T2, W1, W2, and Alpha in a pulley problem?

To find T1 and T2, you can use the equations of rotational motion or the concept of mechanical advantage. W1 and W2 can be determined by measuring the weights of the objects or using known values. Alpha can be calculated using trigonometric functions or by measuring the angle of rotation of the pulley.

5. What are some real-world applications of pulleys?

Pulleys are used in a variety of applications, such as elevators, cranes, and workout equipment. They are also commonly used in the automotive industry for power steering and in construction for hoisting materials. In the home, pulleys can be found in window blinds, clotheslines, and garage door openers.

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