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-   -   Upthrust in water with different gravity (http://www.physicsforums.com/showthread.php?t=477836)

 Scarlet_pat Mar2-11 10:13 PM

Upthrust in water with different gravity

1. The problem statement, all variables and given/known data

A small cork floats in water, exactly half submerged, on Earth. If the container,
water and cork were all transferred to a place where the acceleration due to
gravity is less than that on Earth, would the submerged proportion of the cork
be greater. stay the same or become less?

3. The attempt at a solution

The submerged proportion of the cork will become less.

Because the volume remains constant while the weight of the object changed due the different gravity.
the upthrust force will be greater than the force of the object exerted.

Question: is the answer correct? it is quite plausible because the weight of the water has also changed. Does it affect the upthrust force? or volume and destiny are the only elements which will affect the upthrust force of liquid.

thank you very much :)

 gneill Mar2-11 10:33 PM

Re: upthrust-

If the value of g changes, then it affects the weights of all things equally. That includes the weight of the water displaced by a given volume, which determines the magnitude of the buoyancy force.

 Scarlet_pat Mar2-11 10:39 PM

Re: upthrust-

the net upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body. and therefore... the floating object will remains at it's original position ... right ?

 gneill Mar2-11 10:50 PM

Re: upthrust-

Quote:
 Quote by Scarlet_pat (Post 3168059) the net upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body. and therefore... the floating object will remains at it's original position ... right ? thanks for reply :)
The magnitude of the buoyancy force is equal to the weight of the fluid displaced by the body, right.

The weights of the body and the water are both determined by the local g, which behaves as a simple proportionality constant for the underlying masses. The ratios and relationships that determine buoyancy effects remain the same.

 Scarlet_pat Mar2-11 10:58 PM

Re: upthrust-

Quote:
 Quote by gneill (Post 3168080) The magnitude of the buoyancy force is equal to the weight of the fluid displaced by the body, right. The weights of the body and the water are both determined by the local g, which behaves as a simple proportionality constant for the underlying masses. The ratios and relationships that determine buoyancy effects remain the same.
thanks for such sophisticated explanation :)

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