A Simple Physics Question
There are 2 masses of equal mass suspended by a string at the same height. Under mass 1 there is nothing between it and the floor. Under mass 2 there is a compression spring. The spring is fairly weak and is not strong enough to hold the mass at any height. Basically, the spring will be completely compressed when the mass is released. The actual spring rate is not important just that it has something above 0 lb/in.
1. Do the masses accelerate at the same rate when the strings are cut?
2. Which mass hits the floor first? (assume the spring is recessed into the floor and will be fully compressed when the mass reaches the floor)
3. If one is slower than the other, why?
To KEEP IT SIMPLE use the following assumptions:
a. the masses are solids, not liquid or gas
b. the spring is a compression spring which starts at its free height (ie. uncompressed) with no gap up to the mass. it is not in tension either.
c. this event takes place in a vacuum
d. this event takes place on earth, use 9.81 m/s^2 for acceleration due to gravity. no black holes, etc.
e. the temperature, materials, humidity, etc. are whatever you want them to be. they are irrelevent to understanding the principle. make up some numbers if it makes you feel better.
f. remember this is supposed to be a simple exercise. reading more into is your option to do but is mostly irrelevent to understanding the principles
e. here is a diagram of the problem
http://lh4.ggpht.com/_Vu2Zos0Bs8w/S6LxyZdMhgI/AAAAAAAABfc/Cp...
The problem with all the 9-11 talk
is that people have become so emotional and propogandized that they will vehemently deny the laws of physics. As if these laws were somehow suspended on that day.
It is crucial to get anywhere on this subject to re-educate people on the basic physics of it. No buildings, no planes, just mass blobs, widgets, etc.
Only after that can the nonsense that was given as fact be seriously challenged.
I don't know who was behind 9/11. I can't say for sure who did what. I believed the official story for a few years until I took a step back and looked at it from an engineering stand point. The only thing I can say is I am certain that 2 planes did not bring down 3 buildings in NYC on 9/11.
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Of course its 'A'
This is why 9/11 was clearly an inside job. The SPRING represents the building that the top of the tower had to fall through. Physics laws, which are immutable, demand that the mass will be slowed by the spring because it creates resistance. However, on 9/11 the buidings collapsed at free-fall speed, proving that the "spring" was compromised to lose its springiness. Within a second or 2, the towers should have taken (theoretically, if even possible) over twice as long to collapse. You can believe all the lies you want about 9/11, but physics and science PROVE beyond any doubt that the buildings did not fall because of fire. If, IF, the fie weakened the steel around the fire, the steel on the lower 80 floors, which are made of progressively THICKER steel, were NOT weakened. Theoretically, for this exercise, the spring in this question should get progressively harder to compress as it compresses.
All the rhetoric and BS in the world can't out wit immutable laws.
9/11 was an inside job and the towers were controlled demolitions, using the planes as a smoke screen to take the eyes of of what really happened. Building 7 clearly proves this as it fell at free-fall and was mever hit by a plane.
It's now or never...time to hit the streets and spread the truth!
It seems this really should be a video
Many people are visual and will understand much more easily if they see this happening.
Show a lego tower and damage it near the top by removing enough pieces for the top to collapse. Freeze the video. Then propose two outcomes and ask which would be correct before showing what actually happens;
Ron Paul's Convention Speech
Newtons cradle.
I double dog dare anyone to try this with their own balls!
http://www.youtube.com/watch?v=N23hWICdgsU
Knowledge is power, action is love.
Damn don't know physics. Been
Damn don't know physics. Been studying to much economics :)
Commerce with all nations, alliance with none, should be our motto. - T. Jefferson rЭVO˩ution
"Everyone wants to live at the expense of the state. They forget that the state wants to live at the expense of everyone.” - BASTIAT
however it should be pretty
however it should be pretty simple.
Both fall at the same speed, everyone knows objects fall at the same speed,
until the second hits the spring and it slows down every so slightly.
Even a slight resistance is still resistance enough to slow an object.
Commerce with all nations, alliance with none, should be our motto. - T. Jefferson rЭVO˩ution
"Everyone wants to live at the expense of the state. They forget that the state wants to live at the expense of everyone.” - BASTIAT
This is a trick question. It's an analogy ...
the "spring" is the US dollar.
And when the strings are cut, things that are held up by the dollar will fall (almost) as fast as if they were held up by nothing.
Sweet !
err, no... not sweet ;-(
Who was buried in Grant's tomb?
"What part of 'free fall' do you not understand?"
That's what I ask deniers. Keep going my friend. Stay logical.
Buildings can collapse by fire
if constructed and designed to collapse by that means.
OH, you got to get up early.
there are no buildings in the this problem
where do you get that? keep to the problem
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they were built out of fuse-links?
that answers it! and by golly here I was, all this time, thinking we just used those on fire dampers!
[a fuse-link is a device used to break electrical circuits or release spring loaded dampers based on temperature.][we also use them on pressure vessels]
basically a piece of solder melts.
Knowledge is power, action is love.
It is all how the cross tie fits on it's support.
fire heats a length of beam and sags in the middle pulling the ends off of it's support. Of course to get an object or mass to fall square to the Earth All supports would need to be breached ALL at the same time. The force of air escaping would cushion the fall and would have to be released equally around the square.
Of course this example question states, "in a vacuum". So if a vacuum were present then the vacuum would help facilitate the fall. Faster than freefall.
Yes I am familiar with fuse links. electrical or otherwise.
And you cannot start a fire in a vacuum. No oxygen.
in your example, the cross tie no longer fits on its support.
why are you trying to confuse people? I will have to ask, do you even know what a "vacuum" is?
"The force of air escaping would cushion the fall and would have to be released equally around the square."
what are you talking about?
Knowledge is power, action is love.
Obviously someone is confused .
a hollow building or block of mass is occupied by space and air, oxygen. since air is a solid when captured or contained , it must escape to allow a collapse. This is also how an airplane wing functions. The solid air stream under the the wing holds the wing afloat. the lighter longer air stream above makes for lift.
And yes, a vacuum is the absence of atmospheric pressure or the decrease of same. 30 psi. av. The only vacuum created would be on the top side of any plane (like a floor or roof), in a collapse or freefall. The underside would have a resistant pressure trying to escape. Pressures above the normal atmospheric level. Gravity is adding the force.
that would be 30 in,hg
like in inches of mercury.
I will be nice, do you have ANY idea what an HVACTech does? and yes, I am old school. I understand pneumatic force, very well thank you. what you are talking about are fan laws. and yes, I do happen to know how they move air.
30 psi av. nice try, would that be 30 PSIG? or PSIA?
Knowledge is power, action is love.
Stop it .
you win by default, your an expert. I'm just a shepherd boy.
cavitation was next, big boy.
I try to help people, NOT confuse them.
Knowledge is power, action is love.
Answers
No. Mass 1 accelerates at a faster rate.
Mass 1 hits the floor first.
Mass 2 has a lower acceleration and a lower speed because there is an opposing force acting upon it, whereas Mass 1 is only acted upon by the force of gravity.
we have a winner
now apply that to the real world.
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Applying it to the real world
So if a top portion of a building is moving towards earth and this portion is crushing the remainder of the building below it, there will be a force that opposes the force of gravity.
So in this case, the top portion of the building will not accelerate at free fall because some of its energy is going into crushing the building below it.
On the other hand, if a top portion of a building is moving towards earth and it is falling at free fall acceleration, this indicates that there is no resistance below it.
Therefore, we conclude that the bottom portion of the building is being quickly removed out of the way, so as not to cause any resistance or oppose the top portion of the building as it falls.
This quick removal can only be created by precisely timed explosives.
It depends whether the spring underneath, lengthens the mass.
compression rate and height. with the spring underneath the mass the mass will never hit the floor, the spring will.
your whole question is not physics but rather magic.
not physics? really?
this is basic physics, high school stuff and is absolutely physics.
reading way to much into the problem. what does lengthen the mass mean?
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"lengthen the mass"
has to do with Pythagoras theorem.
"the angle, of the dangle. equals the mass of the a..."
and, that is why we call it a pie!
silly!
Knowledge is power, action is love.
You could liken the pressure from the spring
to a small, weak rocket thruster. It would slow the acceleration of gravity on a falling object that compresses it. The free-falling weight would strike the floor or ground first.
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A bump for those new to DP
Remember this is a simple physics problem, nothing more.
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When I play Jenga
When I play Jenga, if I take out too much support in an area, it ALWAYS falls in its own footprint.
Springs are designed to return to their original shape, when at rest.
WOW
self imploding Jenga blocks thats one crazy expensive way to play Jenga a set you on get to stack once!!!
Mine always topple to one side but I get to use mine again.
I am guessing you do not grasp what straight down into its own foot print means. Otherwise i would have to assume your a horrible liar. lol
The Abuse of Greatness is when it disjoins remorse from power. - Shakespeare
I am.
I am a horrible liar.
I'm not capable of destroying myself in that manner.
Sarcasm, on the other hand, is a great tool to make a person think "WTF?".
indeed
I was hoping it wasn't sarcasm though then I was going to ask to borrow a large sum of money to purchase my own imploding Jenga set, which I would promptly use to buy an expensive new car of course.
The Abuse of Greatness is when it disjoins remorse from power. - Shakespeare
Question is flawed
Springs store energy. This confounds the issue.
The lower portions of the buildings only need to demonstrate the property of INERTIA to make your argument.
Remember, you must point out the fact shown on YouTube video "WTC7 in Freefall: No Longer Controversial" that it really is freefall.