Tension in cable and reaction force

In summary, the problem involves reconciling the moments involving the Z-component into the moment equation around point A. The x component is along the line of point A, causing the moments to be zero. In 2-D moments, the x and y components cause rotation in the same direction, but with 3-D moments, the z component will rotate in a different direction. The solution involves taking a moment with respect to point B and using vector analysis.
  • #1
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Homework Statement


Homework Equations


The Attempt at a Solution


For this problem, what I am confused about is the fact that the Z direction parts of the tension will tend to rotate in a direction different from the Y components of the tension and the 850 lb vertical force. I am not sure how to reconcile the moments involving the Z-component into my moment equation around point A, which I know should be zero. The x component is along the line of point A, so there moments must be zero.

I remember solving 2-D moments and the x components and y components will cause rotation in the same direction, but with 3-D moments it appears the z component will rotate around a different direction than the y component will, so it seems unlikely that they can be added together like the x and y components can be in 2-D torques.

I know the page is cut off, but I don't get the right value when I do it this way. I know the part about the forces is correct, there is something that I am missing though with respect to taking a moment around point A, which I want to do in order to get rid of the reaction forces at A.
 

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  • #2
Taking a moment with respect to point B should give you more simple equations.

If you are doing scalar analysis, you should break your moment into Mx, My, Mz. Use M = r x F instead for vector analysis.
 
  • #3
Thanks, I took the moment at point B and got it solved
 

1. What is tension in a cable?

Tension in a cable is the force that is transmitted through the cable when it is pulled at both ends. It is a measure of the tightness or stiffness of the cable and is often expressed in units of pounds (lb) or newtons (N).

2. How is tension in a cable calculated?

Tension in a cable can be calculated using the equation T = F * L, where T is the tension, F is the force applied to the cable, and L is the length of the cable. This equation assumes that the cable is ideal, meaning it has no weight and is perfectly flexible.

3. What factors affect tension in a cable?

The tension in a cable is affected by several factors, including the amount of force applied, the length and weight of the cable, the angle at which the cable is pulled, and the material properties of the cable (such as its elasticity and strength).

4. What is the reaction force in a cable?

Reaction force in a cable is the force that is equal in magnitude and opposite in direction to the tension in the cable. It is the force that is exerted by the cable on any object or structure that is attached to it.

5. How can tension and reaction force be measured?

Tension in a cable can be measured using a tension meter, which uses a calibrated spring to measure the force applied to the cable. Reaction force can be measured using a force gauge or load cell, which can measure the amount of force being exerted on the cable by the object or structure attached to it.

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