Basic mechanics question -- Two cables supporting a stage light

In summary, the student is struggling with a physics question regarding the sum of forces and is seeking assistance. They have attempted to solve it using a scale drawing and the head to tail method, as well as multiplying the given values, but have not been successful. They are looking for guidance in finding the resultant force and have received a hint to consider the sum of all the forces.
  • #1
Krashy
30
5

Homework Statement



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Homework Equations


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The Attempt at a Solution


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Hi, this is a question from the OCR for self studying purposes. Only the first question is relevant for me. I know that the solution is 120N in the opposite direction to the weight, but i can't get to this solution. There is no calculation in the solution so i tried doing it with scale drawing and the head to tail method, but it didnt work. I also tried to multiply the 120N by the stage light with the cosine of the angle between the vectors but the angles are above 90 degrees so i won't get a useful solution.

All the other questions in that topic were really easy so i guess its something fairly simple that i need to do. I hope someone can help me. Thank you very much in advance.
 

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  • #2
Hi Krashy and welcome to PF.

What is the sum of all the forces? Hint: Note that the resultant that you seek, when added to the 120 N down, should give you that sum.
 
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  • #3
I got it, thanks again
 

What is the purpose of two cables supporting a stage light?

The two cables provide stability and balance to the stage light, ensuring that it stays in place and does not fall or tip over.

What is the relationship between the tension in the cables and the weight of the stage light?

The tension in the cables must be greater than the weight of the stage light in order to hold it up and keep it from falling. This is known as the Principle of Equilibrium.

What factors affect the tension in the cables?

The tension in the cables is affected by the weight of the stage light, the angle at which the cables are attached to the light, and the strength and quality of the cables themselves.

How do you calculate the tension in the cables?

To calculate the tension in the cables, you need to know the weight of the stage light, the angle of the cables, and the gravitational acceleration (9.8 m/s^2). The formula for tension is T = W / sinθ, where T is the tension, W is the weight, and θ is the angle.

What is the maximum weight that can be supported by the two cables?

The maximum weight that can be supported by the two cables depends on the strength and quality of the cables, as well as the angle at which they are attached. It is important to follow safety guidelines and not exceed the weight limit recommended by the manufacturer.

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