Do Floating Objects Have 'Weight'?

[inventor]

There are specific circumstances where warm water does freeze before colder water.


I don't really know this, but my guess would be the lower pressure, bringing it closer to it's triple point. My other guess would be it's related to the theta-w.

No, it's hillbilly logic. If the conditions are right for snow, then the air generally has lower humidity, and 'dewpoint'. That's not why it happens, but it seems to be a good corallary.

We're not gonna argue the warm water thing.

Water doesn't freeze at 32* F. Ice melts at 32* F.

Guessing you aren't an air conditioning guy?

 

[Subcooled]

Say for example, you've got an aquarium that weighs 100 pounds when full of water. If you were to float a 10 pound object inside of that aquarium, does the whole system now weigh 110???

Eat a 10 pound object. It will then float inside you. Will you now weigh more?

 

[aquaregia]

Water doesn't freeze at 32* F. Ice melts at 32* F.

How about "water may freeze at 32F, ice does melt at 32F"?

 

[Walter]

What Walter is saying is this:

Nope. You are taking a very simple concept and complicating it.

Take an imperial bathroom scale. Put an object on it that weighs 180 lbs. It will register 180 lbs. Take the scale and the object to the moon. It will register 30 lbs. It will register 30 lbs because in 1/6 G it actually weighs 30 lbs. No need for recalibration. If you were using a balance, it would register 180 lbs on the Earth and on the moon. It would be correct on the Earth and incorrect on the moon.

Take a metric bathroom scale. Put the same object on it (180 lbs). It will register approximately 82 kg. Take the scale and the object to the moon. It will register approximately 14 kg. It will register 14 kg because it is measuring the force on the scale. If kg was a measurement of weight, it would be correct. Since kg is a measurement of mass and the object's mass has not changed, the scale is wrong. It's mass is still 82 kg. Its weight has changed, but its mass has remained the same. If you were using a balance, it would register 82 kg on the Earth and on the moon. It would be correct on both the Earth and the moon.

Really? Did you not get that?

Really. Please explain how scales know they are on the moon.

 

[Blackwood]

Nope. You are taking a very simple concept and complicating it.

Take an imperial bathroom scale. Put ... -SNIP-

... I thought that's what I said. If a scale which registers force is calibrated for mass, it's done given a specific g, and will incorrectly display mass given a different g.

 

[The Kraken]

fftopic:

Inventor, I love your avatar.
If my wishes could be fulfilled, I'd have a Catalina (PBY) and would live the rest of my life flying about the mid and south Pacific diving.

the K

 

[mikemill]

Please explain how scales know they are on the moon.

Assume an electronic scale with a 1Kg reference weight that it can independently measure the force for. It also has the standard earth gravity value stored.

You turn the scale on, it measures the force of the 1Kg weight. From this it can figure out the local acceleration (F = ma). You step on the scale and it measures the force. From there it can show you the local weight, mass, earth weight, or pretty much whatever you want.

 

[myscubastory.com]

Yup! Basic laws of physics - they also teach you stuff like this and buyancy rules when you take a divemaster or instructor course

 

[inventor]

A scale can't 'know' it is on the moon. The statement meant; A scale will not think to itself, 'Oh, I'm on the moon, I'd better recalibrate.'

You're obviously trolling.

@Kraken

Thanks! My dream aircraft, just buzzing around the Carribbean, diving.

It's actually this aircraft, the NEW Goose!

Antilles Seaplanes, The Official Website for the G-21G Super Goose

Too bad they are out of business!:depressed:

(What? Can't get no love for the signature?)

 

[ev780]

What if the cockpit is open?



What if the fly is flying above an open bomb door?

If the fly is over the bomb door then it does not. The down force needed to keep the fly aloft is not being applied to the aircraft but to the earth below.

If the fly is flying, then it's weight can not be added to the overall weight of the plane as it is supporting it's own weight by means of lift generated from its wings. There may be some downward force generated by the fly that can cause weight fluctuations, but the static total weight will remain unchanged if the fly flys out the window.

If the down force keeping the fly aloft is applied to the aircraft then the weight is included. When he flys out the window then the force is no longer being applied to the aircraft and the plane will be lighter.

Remember Newtons Third law!!!