Spring scale w/ Different Forces

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When applying 50 pounds of force to one side of a spring scale and 40 pounds to the other, the scale will read the difference in tension, which is 10 pounds, not an average. In the case of a pipe with a supply pressure of 50 psi and a return pressure of 40 psi, the pressure on the sidewall would be influenced by the higher supply pressure, resulting in a net pressure of 50 psi. The tension in the rope scenario is misunderstood; it does not simply add up but reflects the force exerted. If both ends of the rope are pulled with 50 pounds of force, the tension would equal 50 pounds. Understanding these principles is crucial for accurate measurements in both mechanics and plumbing.
torq123
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I have two questions that I think are analogous (tell me if they are not).

1. If I have a spring scale and apply 50 pounds of force to one side and 40 pounds to the other, what would it read and why? (I think it will read 45 pounds because that is what the tension would be if it were a rope).

2. If I have a pipe with a supply pressure of 50psi and a return pressure of 40psi, what is the pressure on the sidewall of the pipe.

These are not homework questions--I was doing some plumbing recently in the lab and it got me thinking...
 
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I think the tension in the rope is 90 lb, and same for the spring scale.
 
UltrafastPED said:
I think the tension in the rope is 90 lb, and same for the spring scale.
What if you pulled both ends with 50 lbs of force?
 

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