but fish != birds and water != air. Yet the principle remains the same. What a crazy world we live in...
Because in order to counteract the force of gravity, you're exerting an equal but opposite downward force. A scale won't register it because the downdraft spreads out so much, but if you're in a sealed shipping container, well, I don't know.
Originally posted by: Canai
or maybe half a mole of hummingbirds even?
Now that's a big box!:Q
oh yes we are! You don't think a container with a vacuum in it weighs less than an "empty" container full of air?
well, time to head to class and put a stop to the mindless drivel pouring forth from my mouth, er hands. Oh wait, it's a discussion class: confusing statements ftw or all!
Originally posted by: jagec
Because in order to counteract the force of gravity, you're exerting an equal but opposite downward force. A scale won't register it because the downdraft spreads out so much, but if you're in a sealed shipping container, well, I don't know.
exactly... it's a complicated aerodynamics problem since it depends how the air being pushed downwards by the hummingbirds interacts with the holes at the top of the box... chances are that enough air will exit through those holes to reduce the force below 90lbs, so the ship won't sink, but who knows for sure.
But stuff weighs less in water than it does out of water. . .for example if you put a scale at the side of the pool and another scale in the bottom of a 6 foot deep pool. You weigh your self out of the water and you weigh, lets say 175 pounds. You now get int the pool and stand on the scale and weigh yourself, does it still register as 175 pounds? I think not because you weigh less in water. But lets say it were something denser than water like a solid lead sphere which weighs 100 pounds out of water. If you weigh it again in water, would it still weigh 100 pounds?
How much does the rope weigh(that you're tying the birds down with)? What about the straps on the box to keep it secured?
But floating objects implies that the objects themselves are actually weightless (or at least less dense than the medium that surrounds them) and so need not exert any force to remain hovering. Hummingbirds are not weightless and so must expend energy to thrust themselves upward. . .
Well that makes sense, assuming the birds were not hovering already when their box was put on the boat. But what if the birds began hovering first and THEN the container was placed on the boat with the birds still hoveirng?
Originally posted by: hiredgoons
I'd like to see a 10 lb box that can hold half a mole of hummingbirds
Well what if the box were constructed of reynolds plastic wrap and was really more of a bubble. . .you could make a pretty big plastic wrap bubble with 10 pounds of plastic wrap.
DrPizza
Administrator Elite Member Goat Whisperer
As mugs and fleshconsumed have pointed out, this is a pretty simple physics problem. You can't "prove" the boat won't sink; because you're wrong. Your coworker is correct.
DrPizza
Administrator Elite Member Goat Whisperer
Here's a reference:
advancedphysics.org
The box would exert the same amount of force on the boat. Note that in that discussion by physics nerds that one person even points out the E=mc^2 equivalence and notes that at a higher energy state, the mass is greater. He forgot to account for a slight decrease in mass to result in this energy. Regardless, the physics nerds don't even for a moment entertain the thought that the box weighs less.
This is basic physics. A couple of free body diagrams should point out the solution. If not, your physics teacher sucked.
Oh, and the sides do end up mattering, of course.
advancedphysics.org
The box would exert the same amount of force on the boat. Note that in that discussion by physics nerds that one person even points out the E=mc^2 equivalence and notes that at a higher energy state, the mass is greater. He forgot to account for a slight decrease in mass to result in this energy. Regardless, the physics nerds don't even for a moment entertain the thought that the box weighs less.
This is basic physics. A couple of free body diagrams should point out the solution. If not, your physics teacher sucked.
Oh, and the sides do end up mattering, of course.
JulesMaximus
No Lifer
- Jul 3, 2003
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Originally posted by: mugs
Considering how little hummingbirds weigh that has to be a pretty big box, and if this big box fits on a boat I would have to wonder why that boat is only capable of holding 100 pounds of cargo.
That's over 13,000 hummingbirds
In a 10lb box. :laugh:
Originally posted by: ahurtt
Originally posted by: hiredgoons
I'd like to see a 10 lb box that can hold half a mole of hummingbirds
Well what if the box were constructed of reynolds plastic wrap and was really more of a bubble. . .you could make a pretty big plastic wrap bubble with 10 pounds of plastic wrap.
Enough to hold ~6.0223/2 x 10^23 hummingbirds? We're talking about a "box" of hummingbirds that's probably not too many orders of magnitude off of the volume of the Earth itself.
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