# Tensions of cable over a pulley

1. Nov 27, 2013

### aerograce

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

2. Nov 27, 2013

### SteamKing

Staff Emeritus
No figure is attached to your post.

3. Nov 27, 2013

### aerograce

Here it goes:)

#### Attached Files:

• ###### 02431.png
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4. Nov 27, 2013

### Staff: Mentor

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. Nov 27, 2013

### sophiecentaur

@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??