Tensions of cable over a pulley

In summary, the conversation discusses a figure with a section containing three pin-connected bars and two pulleys connected by a string. The individual is questioning the tension along the string and concludes that it would not be the same due to the presence of two concentrated loads exerted by the pulleys. However, if the system is ideal with frictionless pulleys and a massless string, the tension would be the same throughout the string. To justify this, a load would need to be present in the diagram and the system assumed to be in equilibrium.
  • #1
aerograce
64
1
In the figure attached, we have one section which has three bars all pin-connected together and pin fixed on the ground. We have two pulleys connected with the section by string. And we have one string starting from the left fixed pin to the right fixed pin. I am thinking whether the tension along the string will be same or not. I am imagining that, it is a single string with two concentrated loads(Excerted by pulley), so it is not the same. can you help me justify that
 
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  • #2
No figure is attached to your post.
 
  • #3
SteamKing said:
No figure is attached to your post.
Here it goes:)
 

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  • #4
aerograce said:
I am thinking whether the tension along the string will be same or not. I am imagining that, it is a single string with two concentrated loads(Exerted by pulley), so it is not the same.

If the pulleys are ideal frictionless pulleys and the string is an ideal massless string, then the tension in the string will be the same everywhere. If it weren't, then some point in the string would experience a greater pull from one side than the other and would be accelerating - and that's not happening.
 
  • #5
@aerograce.
Your diagram has nothing in it to cause a force - if we are assuming that everything is 'ideal'(massless and frictionless). You would really need to put a load somewhere and then you could calculate the forces on the pulley supports, for instance, and the tension all along the string could be assumed to be the same.
We are assuming that the system is in equilibrium??
 

Related to Tensions of cable over a pulley

1. What is the tension of a cable over a pulley?

The tension of a cable over a pulley refers to the amount of force that the cable is exerting on the pulley. It is typically measured in units of newtons (N) or pounds (lbs).

2. How is the tension of a cable over a pulley calculated?

The tension of a cable over a pulley can be calculated using the formula T = W + Ma, where T is the tension, W is the weight of the object being lifted, and Ma is the acceleration of the object.

3. What factors affect the tension of a cable over a pulley?

The tension of a cable over a pulley can be affected by several factors, including the weight of the object being lifted, the angle of the cable, the length and thickness of the cable, and the friction between the cable and the pulley.

4. How does the angle of the cable affect the tension over a pulley?

The angle of the cable can greatly affect the tension over a pulley. As the angle increases, the tension also increases, since the weight of the object is distributed over a larger area. However, if the angle becomes too steep, it can cause the cable to slip off the pulley or cause excessive friction.

5. How can the tension of a cable over a pulley be controlled?

The tension of a cable over a pulley can be controlled by adjusting the weight of the object being lifted, changing the angle of the cable, or using a different type of pulley system. Additionally, using a thicker and stronger cable can also help to control the tension and prevent it from exceeding safe limits.

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