Calculating Tension for Beginners

  • Thread starter WakeOfBeauty
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In summary, the conversation discusses a student's struggle with understanding tension and a homework problem involving a street lamp supported by two wires at an angle. The student asks for help and is advised to draw a free body diagram and resolve force vectors to solve the problem. The student eventually figures out the solution on their own, highlighting the importance of learning and understanding the material for exams.
  • #1
WakeOfBeauty
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My teacher is a dumbass and a horrible teacher. I swear he never taught us how to find tension and the "textbook" gives us long stories about little Billy and Bobby but never explains how to DO the problems. I need help for this question. Please explain if you can


Homework Statement



A street lamp weighs 150N. Its supported by two wires that form an angle of 120 degrees with each other. The tension in the wires are equal.
a) what is the tension in each wire supporting the street lamp?
b) If the angle between the wires is reduced to 90 degrees, what is the tension in each wire?

2. Formulas Needed

no clue. sorry

3. Attempts
I don't know any of this so I couldn't even attempt to do it. I don't know where to even start
 
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  • #2
Draw the free body diagram with all the forces acting. Then split then tensions in the wires into x and y components. Then use the fact that for equilibrium, the sum of the forces in a specified direction is zero.
 
  • #3
Welcome to PF.

Maybe you shouldn't be so hard on your teacher? At least the teacher likely knows how to figure the problem?

But as to equations this is a matter of resolving the force vectors from the information given. Drawing a diagram should be helpful.

You know what the vertical components of the tension must be in the two lines, hence you should be able to figure the Tension itself.
 
  • #4
this doesn't help at all.
 
  • #5
https://www.physicsforums.com/showpost.php?p=1042781&postcount=2
 
  • #6
'kay, i figured it out on my own already. bye :)
 
  • #7
That's great. The system works and you learned how to solve the problem.

If someone had told you the answer you might have difficulty come exam time.
 

Related to Calculating Tension for Beginners

1. What is tension and why is it important to calculate?

Tension is a measure of the force exerted on an object that is being pulled or stretched. It is important to calculate tension because it helps us understand the stability and strength of structures, as well as the behavior of objects under different forces.

2. How do I calculate tension?

To calculate tension, you will need to know the weight of the object in question, as well as the angle and direction of the force acting on it. You can then use the formula T = W * sin(theta), where T is the tension, W is the weight, and theta is the angle between the force and the object.

3. What units are used to measure tension?

Tension is measured in Newtons (N) in the metric system, and in pounds (lb) in the imperial system. Both units represent the amount of force needed to keep an object in equilibrium.

4. Can tension be negative?

Yes, tension can be negative. This occurs when the force acting on an object is in the opposite direction to the direction of motion. In this case, the tension is pulling the object back instead of moving it forward.

5. How does tension affect different materials?

Tension can have different effects on different materials. Inelastic materials, such as steel, will experience a change in shape or break when subjected to high tension. Elastic materials, such as rubber, will stretch under tension but return to their original shape once the force is removed. The strength and stiffness of a material also determine how it will react to tension.

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