Working out tension of string holding a ball underwater

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Homework Help Overview

The discussion revolves around a physics homework question involving a submerged ball attached to two strings in a swimming pool. The problem requires calculating the tension in each string, considering the buoyancy of the ball and the forces acting on it.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster questions whether to use buoyancy or tension formulas in their approach. Some participants suggest performing a force balance on the ball, noting the gravitational and buoyancy forces at play.

Discussion Status

Participants have provided guidance on considering the forces acting on the ball, indicating that a force balance is necessary. There is acknowledgment of the need for equal forces since the ball is not moving, but no explicit consensus has been reached on the exact approach to take.

Contextual Notes

The original poster's question includes a hint about looking up the density of water, which may imply that specific values or additional information are needed to proceed with the calculations.

Alice Martin
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I have a physics homework question that i need help with;
A submerged ball of negligible mass is attached to the bottom of a swimming pool by two strings as shown. The volume of the ball is 5000cm^3. Calculate the tension in each string. (hint you need to look up the density of water)

How do i do this? Do i use the buoyancy of the ball or the tension formula?

The
Screen Shot 2016-04-25 at 4.13.49 pm.png
triangle with the base being the bottom of the pool and the ball being attached to the top vertex with a 60 degree angle
 
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What you need to do is a force balance on the ball. :wink:

So there is a gravitational force, a buoyancy force and tension forces all acting on the ball, which is not moving. What does that tell you?
 
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mfig said:
What you need to do is a force balance on the ball. :wink:

So there is a gravitational force, a buoyancy force and tension forces all acting on the ball, which is not moving. What does that tell you?
Thank you! That is a really simple way of putting it. I did not even think about the fact that the forces must be equal!:wink:
 
Hi Alice! Welcome to PF!

I've gone ahead moved your thread to the homework forums, but in the future please make sure you place your question here (or in whichever homework forum is appropriate) and that you fill in the template provided when you create a thread in the homework forums.

@mfig, please use the report feature to report homework posts outside of the homework forums instead of replying to them. Thank you!
 

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