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Originally Posted by Vansquish

Quote:

Originally Posted by graywolf624

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However, in the real world, there is drag, and items will obviously fall at different speeds, and the more aerodynamically efficient ones will fall quicker. Still, weight will not be relevant. Right?

Let me say first that I have very little background in fluids. In terms of modeling it with physics, your starting to get over my head when you get into drag.

That being said I am sure the mass of the object falling is important, but other aspects are as well. With aerodynamic drag there are so many factors you probably could not get the same result with 2 runs of the same object. Some of these include the surface area of the object, shape of the object, and speed of the object.
Then you have density of the air, temperature of the air, pressure, direction of air flow, etc (which are all interrelated.)

The air provides a force to the object pushing up.. the object pushes down on the air. Remember from the equations above the force of the falling object is f=m1a where a is a constant 9.8 m/s^s.
So now we pick a heavier m1. The force of the heavier object falling is now higher since we just showed its non earth relative acceleration is constant. This means if it hits the air and encounters the same friction force (aka all else equal), the net force pushing downwards afterwards will be higher then that of a lighter object. A great F with the same mass means a greater acceleration. Thus a heavier object all else being equal will have a higher resistance (momentum) to the slowing effect of the airodynamic drag.

Info on calculated drag and the like.
http://hypertextbook.com/physics/matter/drag/

... Sounds about right to me (says the physicist).

As far as Schroedinger's cat is concerned...

The infamous Schroedinger's cat problem is a thought experiment that has applications to quantum mechanics and various other high-level strains of physics.

Basically it is this:
We place a living cat into a steel chamber, along with a device containing a vial of hydrocyanic acid. There is, in the chamber, a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat. The observer cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. Since we cannot know, the cat is both dead and alive according to quantum law, in a superposition of states. It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive). This situation is sometimes called quantum indeterminacy or the observer's paradox: the observation or measurement itself affects an outcome, so that it can never be known what the outcome would have been if it were not observed.

Thanks for explaining the cat. Your explaination was better that what I read on line.

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Originally Posted by saadie

Do heavier objects "fall" faster?

well ... as i see it .. not being a dork and all ...

heavier objects acclerate to terminal velocity faster then lighter objects .... ;)

that is if you take out wind speed drag coefficients and shit .... like you read in the science books back in school " In Perfect Condition " .. ;)

Nope...terminal velocity is deteremined by the fact that there IS wind resistance (or drag if you like). In the most sterile of conditions, i.e. a vacuum, a 25lb weight and a feather would fall at rates indistinguishable from each other. Now...the argument leveled earlier on in this thread that suggests that if you have two very massive objects exerting gravitational pull on each other, that the rate at which the two closed distance would be substantially greater than an instance in which you had something like a feather and one very massive object is accurate. But with the Earth being as massive as it is (by massive I mean "heavy, exerting gravitational pull"), and everything else that we test being so light, it is unlikely that we would ever be able to see a great deal of difference in the way that anything falls towards the Earth. Thus, following the equations F=GMem/r^2 = m*a and F=GMem/r^2 = Me*a, as posed in Graywolf's post, we arrive at the conclusion (more or less supported empirically) that all objects falling towards Earth experience the same gravitational pull.

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Originally Posted by Vansquish

The infamous Schroedinger's cat problem is a thought experiment that has applications to quantum mechanics and various other high-level strains of physics.

Basically it is this:
We place a living cat into a steel chamber, along with a device containing a vial of hydrocyanic acid. There is, in the chamber, a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat. The observer cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. Since we cannot know, the cat is both dead and alive according to quantum law, in a superposition of states. It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive). This situation is sometimes called quantum indeterminacy or the observer's paradox: the observation or measurement itself affects an outcome, so that it can never be known what the outcome would have been if it were not observed.

In theory and for the sake of philosophical argument, yes.

But how many times has the box been opened and the cat found alive?

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Originally Posted by Vansquish

Most intelligent post in this thread.

:thumbsup: for looking at the whole picture.

yep all the objects experiece the same gravitational put which varies with altitude and blah blah ...... the thing is ... if the weight of one object is 2 and the weight of the other object is 4 .. what then ? .... the gravitational force is not the same on everyobject .. it varies with the weight of the object ;) ... why is a 20 kg weight heavier then a 2 kg weight ? when you try lifting it up :) ... because more gravitational pull is being applied to it
which mean the gravitational pull multiplies according to the weight ;) ..

i donno what i just said :? 8)

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Originally Posted by Vansquish

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Originally Posted by Z3uS

They fall the same speed.

Want to make a test? Just get a book and a sheet of paper, make the book bigger in area than the paper. Then just put the paper on top of the book (on the cover) and let it loose. They will fall together, same speed, same time.

That has more to do with the aerodynamic properties of the book and the fact that the turbulence that forms on top of the book would force the paper to lie flat against the surface of the book.

In fact it was a bad example, but the only one i could come up with at noon.

Well, just remember the hammer and the feather experience done in space. :D

any object will given a long enough fall, reach their terminal velocity by 9,8 m/s/s by http://upload.wikimedia.org/math/6/e...b3a7f16172.png

Vt is the terminal velocity,
m is the mass of the falling object,
g is gravitational acceleration,
Cd is the drag coefficient,
ρ is the density of the fluid the object is falling through, and
A is the object's cross-sectional area.

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Originally Posted by saadie

On the contrary. As stated earlier in this thread, the two masses (say 2kg and 4kg) would experience the same force of gravity and thus, all other things being equal, fall towards the ground from any given altitude, at the same rate. On the other hand, if we actually take into account the gravitational forces applied by the masses on Earth, there is a very small, for all intents and purposes, unmeasureably miniscule difference in the rates at which they would fall. For two VERY massive objects, the rate would be significantly different than for one very massive object and something lighter, like a building, or a bowling ball, or a feather (all of which would be significantly lighter than the "very massive" object.

^ Thank you for further explaining it. 8)

^^ No prob...at least I get to use the Physics degree somewhere! :-D

ok leaving drag out of it, and making the gravitational pulling question a bit more uhmm clear...

the effect we are looking for is more suited for an example in space... imagine placing a planet next to the sun, and then imagine placing another star next to the sun. What we are trying to determine is whether or not the rate of which the gap between the objects close is the same.

i'm suddenly starting to have my doubts

ok...put the Earth next to the Sun...the distance between the two would decrease at rate A, given that the two started from fixed positions and moved in a straight line towards each other (yes, both would be moving as, they would both exert some gravitational pull on each other).

Now put a star the same mass as the Sun next to the Sun, under the same conditions as the Earth-Sun system, the distance between the two would decrease at rate B, which would be GREATER than rate A, as the gravitational forces at work would be significantly greater than in the Earth-Sun system.

Now, the only reason that there is a MEASUREABLE difference between the two is because the Sun (and the star in question) is significantly more massive than the Earth.