Two hanging masses supporting object

  • Thread starter mvr821
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In summary, the problem asks for the weight w1 and angle needed for there to be no force exerted on the hip joint by the leg and cast, taking into account a counterbalance weight w2 of 115 N. Using the equation cot 40 = -x2/115, it was determined that x = -137.05. Using the Pythagorean theorem, the length of the hypotenuse (c) was found to be 178.9, and the tension (T) in the string was calculated to be 81.09. However, this solution was incorrect, as it was based on the assumption that the combined tensions would cancel out the force, which is not necessarily true. The diagram for this problem
  • #1
mvr821
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Homework Statement



The leg and cast in Figure P4.18 weigh 260 N, with the center of mass as indicated by the blue arrow in the diagram. The counterbalance w2 weighs 115 N. Determine the weight w1 and the angle needed in order that there be no force exerted on the hip joint by the leg plus cast.

Homework Equations



This is one of the problems; I can't figure out which equations pertain to this problem.

The Attempt at a Solution



cot 40 = -x2/115
x = -137.05

a^2 + b^2 = c^2
115^2 + (-137.05)^2 = c^2
32007.70 = c^2
178.9 = c

260 - 178.9 = T
81.09 = T

This was wrong. I subtracted because I thought that in order for there to be no force exerted on the hip, the force would have to be zero, so the combined tensions would have to cancel out the force. Where am I going wrong?
 
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  • #2
I forgot to include that the angle for w2 between the string and the horizontal is 40°.
 
  • #3
You have the figure. But we don't know what the figure is.So either try explaining the situation or attach the diagram. I would prefer the latter.
 

FAQ: Two hanging masses supporting object

What is the concept of two hanging masses supporting an object?

The concept of two hanging masses supporting an object is a physics principle that explains how two masses, connected by a string or rod, can support the weight of an object placed on the string or rod between them. This is also known as a pulley system, where the hanging masses act as counterweights to the object.

How does the weight of the hanging masses affect the supporting object?

The weight of the hanging masses directly affects the supporting object. The heavier the hanging masses, the greater the force they exert on the supporting object. This can cause the supporting object to move or experience tension, depending on the direction of the forces.

What is the relationship between the weight of the hanging masses and the supporting object?

The weight of the hanging masses and the supporting object have an inverse relationship. This means that as the weight of the hanging masses increases, the weight of the supporting object decreases. This is due to the principle of conservation of energy, where the total weight of the system remains constant.

Can two hanging masses supporting an object be in equilibrium?

Yes, it is possible for two hanging masses supporting an object to be in equilibrium. This happens when the weight of the hanging masses is equal to the weight of the supporting object. In this state, there is no net force acting on the system, and it remains at rest.

What factors can affect the stability of two hanging masses supporting an object?

There are several factors that can affect the stability of two hanging masses supporting an object. These include the weight and distribution of the masses, the length and angle of the string or rod, and the friction between the string or rod and the supporting object. Any changes in these factors can impact the equilibrium of the system and potentially cause it to become unstable.

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