Statics Problem -- A bucket suspended between two walls by a rope and pulley

In summary, this person is trying to solve a problem involving a pulley, but does not know how to approach it. They are asking for help from others.
  • #1
Nicolas32
5
2
Homework Statement
The pail and its content have a mass of 60 kg. If the cable BAC is 15 m long, determine the
distance y to the pulley at A for equilibrium. Neglect the size of the pulley.
Relevant Equations
Total F=0, Sine Law, Cosine Law
1604666926315.png


I approached this question with a free body diagram.
my Verticle length of BA is y-2
AC= 15-AB
Horizontal length of AC= a; Horizontal length of BA=10-a
I have too many unknowns in this problem and I don't know any directions(angle).
I know that I should start at the weight and try to resolve the AB and AC. But I don't know how the length relates with force.
Can someone just give me directions to approach this problem?
Thank you.
 
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  • #2
Draw a free body diagram for pulley A, showing the forces. This will elucidate the symmetry of the problem. The rest is simple geometry.
If you want more details you must show your work as per the homework policy.
 
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  • #3
Screenshot (10).png

Screenshot (12).png

I tried finding the angle using sine rule(using only lengths),
(10 - y/tanθ)/sin∠BA(-x) = (15-y/sin∠CAX)/sin90 = (y-2)/ sin∠ AB(vertically downwards)
 
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  • #4
hutchphd said:
Draw a free body diagram for pulley A, showing the forces. This will elucidate the symmetry of the problem. The rest is simple geometry.
If you want more details you must show your work as per the homework policy.
 
  • #5
Nicolas32 said:
View attachment 272249
View attachment 272250
I tried finding the angle using sine rule(using only lengths),
(10 - y/tanθ)/sin∠BA(-x) = (15-y/sin∠CAX)/sin90 = (y-2)/ sin∠ AB(vertically downwards)
Your notation is a bit hard to decipher, but you appear to be aware that AC and AB make the same angle to the horizontal.
Similar triangles?
 
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  • #6
haruspex said:
Your notation is a bit hard to decipher, but you appear to be aware that AC and AB make the same angle to the horizontal.
Similar triangles?
I was not aware of that. So if the item is in equilibrium, this causes the angles from the two strings to be equal to each other? With this info I can solve it. I'll be posting soon.
 
  • #7
Nicolas32 said:
I was not aware of that. So if the item is in equilibrium, this causes the angles from the two strings to be equal to each other? With this info I can solve it. I'll be posting soon.
This was what drawing the FBD per post #2 was supposed to show you.
 
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  • #8
haruspex said:
This was what drawing the FBD per post #2 was supposed to show you.

I see. My Y was 4.76m.
Thank you for your help.
 
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1. What is the purpose of the bucket in this statics problem?

The purpose of the bucket is to demonstrate how forces act on an object that is suspended between two points by a rope and pulley system.

2. How do the forces act on the bucket in this problem?

The weight of the bucket exerts a downward force, while the tension in the rope exerts an upward force to keep the bucket suspended.

3. How does the angle of the rope affect the forces on the bucket?

The angle of the rope affects the magnitude of the forces acting on the bucket. As the angle increases, the tension in the rope and the weight of the bucket also increase.

4. What is the relationship between the weight of the bucket and the tension in the rope?

The weight of the bucket is equal to the tension in the rope when the bucket is in equilibrium. This means that the forces are balanced and the bucket is not moving.

5. How can this statics problem be solved?

This problem can be solved using the principles of equilibrium, which state that the sum of all forces acting on an object must be equal to zero for it to be in a state of rest or constant velocity. By setting up and solving equations for the forces acting on the bucket, the tension in the rope and the weight of the bucket can be determined.

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