Conceptual Question Regarding Fluids

In summary, the conversation was about how tension created by a submerged ball affects the total weight of the container. The question was to find the total weight of the system, which involves adding the weight of the water, ball, and beaker. One person argued that the tension in the string, which was stopping the ball from floating to the top, should also be subtracted. The other person argued that the tension is an internal force and does not affect the weight of the system. They were unsure who was correct and asked for clarification.
  • #1
Deaddman
5
0

Homework Statement



A friend and I were arguing about how tension created by a submerged ball affects the total weight of the container.

Homework Equations



I couldn't find anything similar to the situation, so I drew a quick picture to better illustrate the situation :D

Fluidsproblem.jpg


A string is attached to the bottom of the beaker, and is stopping the plastic ball from floating to the top.

The Attempt at a Solution



The question was to find the total weight of the system. Clearly you need to add the weight of the water, the ball, and the beaker, but my friend says you also need to subtract the tension in the string, because it is pulling up on the beaker. I disagree. I argue that the tension pulling on the beaker is an internal force, so it does not affect the weight of the system at all.

Now, I can honestly see either him or me being right. I am unsure, which is what motivated me to post here, in hopes that someone could clear this up.

Thanks for any and all help.
 
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  • #2
You are most certainly correct deaddman, for the same reason that you can't fly by lifting up on your boot straps...
 
  • #3
Thanks very much for the quick reply, zhermes.

Cheers :)
 

1. What is a fluid?

A fluid is a substance that can flow and take on the shape of its container. This includes liquids and gases.

2. How is pressure related to fluids?

Pressure is the force exerted by a fluid on its surroundings. It is directly related to the density and depth of the fluid.

3. What is the difference between laminar and turbulent flow?

Laminar flow is smooth and orderly, with layers of fluid moving in parallel. Turbulent flow is chaotic and irregular, with eddies and swirls.

4. How does viscosity affect the flow of a fluid?

Viscosity is the measure of a fluid's resistance to flow. The higher the viscosity, the thicker the fluid and the slower it will flow.

5. How does Bernoulli's principle explain the lift of an airplane wing?

Bernoulli's principle states that as the speed of a fluid increases, its pressure decreases. This explains how the curved shape of an airplane wing causes the air to move faster over the top, creating lower pressure and lift.

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