# Finding the tension of a support cable to balance the beam

• JohnTheGreat101
In summary, the conversation discusses finding the upward force of the cable in a problem involving a beam and a cylinder. It involves finding the center of mass of the beam and calculating the torques due to gravity, the cable, and the cylinder's weight. The final calculation results in the force of the cable.

#### JohnTheGreat101

Homework Statement
Find the tension in the support cable needed to balance the beam
Relevant Equations
0=tc + tbl - tbr - tcyl
I know the answer is 170 but I am not sure how to get there. I tried doing things backwards
g=9.8
t = fr = mgr
0= 170 + tbl - tbr - 5x9.8x1.5
0= 170 + tbl - tbr - 73.5
-96.5 = tbl - tbr
-96.5 = 18*9.8 * 0.2 - 18*9.8*1.4
-96.5 does not equal -211.68

#### Attachments

• physics problem find tension.PNG
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Hint: Where's the center of mass of the beam?

Ok so I found the mass of the cable. mgr/gr = m
170/9.8x1.2 = 14.46 kg.
COM = 5 kg x 1.5m + 14.46 kg x 1.2 / 14.46 + 5 = 1.28 m

There are three forces acting on the beam that create torques about the fulcrum:
• The downward force of gravity on the beam. (Where does it act?)
• The upward force of the cable. (Which is what you are trying to find.)
• The downward force of the cylinder's weight on the beam.
Add up the torques due to these forces.

## 1. How do you calculate the tension of a support cable?

To calculate the tension of a support cable, you need to know the weight of the beam and the angle of the cable with respect to the beam. You can then use trigonometric functions to determine the tension.

## 2. Why is it important to find the tension of a support cable?

The tension of a support cable is crucial in ensuring the stability and balance of the beam. If the tension is too low, the beam may sag or even collapse. If it is too high, it can put unnecessary stress on the beam and potentially cause damage.

## 3. What factors affect the tension of a support cable?

The weight of the beam, the angle of the cable, and the length of the cable all impact the tension. Other factors such as wind and external forces may also affect the tension.

## 4. Can the tension of a support cable be too high?

Yes, the tension of a support cable can be too high. This can put unnecessary stress on the beam and potentially cause damage. It is important to find the appropriate tension to ensure the stability and safety of the beam.

## 5. How do you adjust the tension of a support cable?

The tension of a support cable can be adjusted by changing the angle of the cable or the length of the cable. The weight of the beam can also be adjusted to affect the tension. It is important to carefully calculate and adjust the tension to maintain the balance and stability of the beam.