Upthrust: Weight of Object or Fluid?

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In summary, the conversation discusses confusion about the Archimedes theory and whether the upthrust equals the weight of the fluid displaced or the weight of the object itself. The conversation also touches on the importance of density and mass in determining weight and achieving equilibrium. The participants also speculate on the reality of upthrust and its effect on objects.
  • #1
coconut62
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I got confused with the Archimedes theory.

I want to ask if upthrust equals to the weight of the fluid displaced by the object, or is it the weight of the object itself?

I thought it should be weight of fluid since fluid has it's own density which determines it's mass which in turns affect the weight acting upwards...But i did came across some people who say that it has to be the actual weight of the object in order to achieve equilibrium. :confused:
 
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  • #2
If the upthrust always equals the weight, can anybody ever NOT be in equilibrium? And what happens in reality?
 
  • #3
LOL thanks!
 

1. What is upthrust?

Upthrust, also known as buoyant force, is the upward force exerted by a fluid on an object immersed in it. It is caused by the difference in pressure between the top and bottom of the object, and is equal to the weight of the fluid that the object displaces.

2. How is upthrust calculated?

The upthrust on an object can be calculated by multiplying the density of the fluid by the volume of the displaced fluid and the acceleration due to gravity. This can be expressed as Fup = ρVg, where ρ is the density of the fluid, V is the volume of displaced fluid, and g is the acceleration due to gravity.

3. What is the relationship between upthrust and weight of an object?

Upthrust and weight are directly proportional to each other. This means that as the weight of an object increases, the upthrust on the object also increases. However, if the weight of the object is less than the weight of the displaced fluid, the object will float due to the greater upthrust force.

4. How does the shape of an object affect upthrust?

The shape of an object affects upthrust in that objects with a larger surface area experience a greater upthrust force. This is because a larger surface area allows for more fluid to be displaced, resulting in a greater upthrust force. For example, a flat boat will experience more upthrust than a round ball of the same weight, as the boat has a larger surface area.

5. Can upthrust be greater than the weight of an object?

Yes, upthrust can be greater than the weight of an object. This is why objects that are less dense than the fluid they are placed in, such as ships and balloons, can float. In these cases, the upthrust force is greater than the weight of the object, causing it to rise and float on the surface of the fluid.

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