Im sorry to bring this up again, im sure you are all bored stiff with the whole 'Do heavier objects fall faster than lighter objects' thing. I bring this up as I understand very little about anything in the previous threads and sat there like the 15 year old gorm i am Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! (but it looks very interesting, I like that sort of stuff). Im in year 11 and going to take my GCSE's in a few months time... so the teachers have decided to pile the work on now, especially in science. For the coursework, we have to change the weight of a paper cone (using plasticine balls inside the cone) and drop it from 2m high, timing how long it takes to reach the floor. My results clearly show that the heavier ones reached the ground first, but i would like to know WHY. Sorry again, but could you reaaaly go back to basics to explain this? Thanks, Dale.
The force caused by the friction between the cone and air, and thats slowing the cone down, is always the same. It depends only on the shape and size of the cone, not on its mass. The gravitational force, thats accelerating the cone towards the ground, on the other hand depends on the mass of the cone (F=mg). So as the mass of the cone gets bigger, the accelerating force gets bigger and the frictional force stays the same. And the resultant force of the two, thats causing the actual acceleration gets bigger too. Therefore the net acceleration of the cone depends on the cones mass. If you were to do the test in vacuum, there would be no friction and the accelerating force would get bigger by the same amount as the mass, so the net acceleration would always be same. g=9,81 m/s<sup>2</sup>
Wind resistance. Friction between the cone and the air. The heavier cone falls fastest because it can push the air out of the way faster and more effective than the lighter cone. They would only fall at the same rate in a perfect vacuum.
F<sub>accelerating</sub>=F<sub>gravitational</sub>-F<sub>friction</sub> F<sub>a</sub>=mg-F<sub>f</sub> a=F<sub>a</sub>/m a=(mg-F<sub>f</sub>)/m a=g-(F<sub>f</sub>/m) You can see from here, that the acceleration will get bigger as mass increases.
My guess hamsterspawn is that your cones are creating a drag, air resistance, so you ahve two parametrs: weight and drag. The textbooks will suggest you redesign your cones to eliminate air friction, or be the best scientist in the class: Report how the imposition of the cone (assuming th teacher designed the cone), designed and constructed as it was, imposed on the experiment was such that the answer to which falls faster, heavy or less heavy objects must remain ambiguous until the educational system is developed enough to provide an adequate vacuum chamber to eliminate any drag force due to air that interfers with the measurements of gravity vs various masses. How many bombs would this cost? That is eliminate all the forces affecting the test mass except gravity;(to be real smart aleck but externally with an appearance of sublime modesty, suspend two cones each with a different weight connected with a sufficiiently long cord suspended from a pulley. The cones will cancel air drag as each moves at the same speed. Then while maintaining a constant "heavy" cone, measure the speed of three or four arrangements all with diffeent weights. For extra credit, try weights that are nearly the same, but use at least two pairs that are heavy and light. This will give measure of sny pulley/cord friction. Geistkiesel
A lot of good answers here but I caution that some are a bit lose in scientific terms. For example he did not ask about acceleration (even if he meant to do so). He specified "Fall" and talks about time to hit the ground. In that format some of these answers are technically invalid. From an objects point of view they all accelerate at the same rate regardless of mass but they do not fall to the ground in the same amount of time. It is immeasureable but you have to recall that the earth reacts and accelerates toward the mass in free fall and the earth accelerates faster for its reaction to a heavier object. Hence the object FALLS TO THE GROUND sooner than a lighter mass. But the ratio of masses i.e. a few Kg falling vs the earth's 6E24Kg where 100 kg falls 100 m, the earth would move toward the falling mass 1.666E-23m. That is falling mass moves 100 m and the earth moves 6.66 billionths of the diameter of a proton.
You will not be able to measure the time difference due to the Earth's movement towards your cone. It is there, but is incredibly small compared to other variables. Don't worry about it. To expand on what fo3 said, the force of gravity on the object is calculated by: Force = G * (m1(object).m2(earth) / d^2) acceleration = F/m1 = G * m2 / d^2 As you can see, the mass of the object has no measurable effect on the force/acceleration due to gravity. The force from air friction is: F = apAv^2 acceleration = F/m1 = apAv^2/m1 It DOES however have an effect on the acceleration due to air friction. The force will remain the same no matter the weight, but that same force will not have as much of an effect on a heavier object (since heavier objects are harder to move). So, I'm not sure how clear that was... so I'll summarize: You have two opposing forces acting on your object. Gravity (down) and air friction (up). Imagine what would happen if you only experience one force at a time. The acceleration down due to gravity is the same regardless of your objects weight. The acceleration up due to air friction is inversely related to weight. Your lighter object will slow down quicker. Hope that helps, let us know if it doesn't.
I think 6.66 billionths of the diameter of a proton was selfevident as being ignorable. But if you read his introduction he stated he was interested in the discussion of this in another thread. Since I participated in that thread I know part of what had his interest was the "Technicality" of such freefall timing. Correct me if I am wrong on that Hampster spawn.
The answer 'why' has nothing to do with the earth moving the diameter of a proton, but of air friction having a larger impact on lighter objects.
I agree but lets see what Hampterspawn says. Was he interested in the prior discussion about this normally disregard fact or not. Being in the 11th grade I am convienced that he understood the principles of a parachute and since he introduced the subject matter referancing the prior discussion and stating these things are of interest to him, I think my post was a proper response.
MacM is suggesting you obtain a gravitonometer cpabl;e of resolution to 23 decimal place. Radio Shack doesn't have anymore of these devices, The bottom line Hamsterspawn is for grading purposes, and if you are graded on a curve, with respect to the other tested students, cleverness is your best avenue to a high score, You might consider approaching the professor, not felow student thay could rip you off. Like an invention, the frst one to register at the patent office wins, most of the time. Buty talk to you main man. Your distaste for the "system" needed no explanation. If tyhe purpose is to skate through with an acceptable grade that will get you to thw university, I suggest another line of work. I am not suggesting you have intrinsic talent for solving physics problems. If you did you would be a memorizer and not proficient in thinking with a mind capable of approachinmg the paramerters of a problem from many rational perspectives. Think the hell out of the problem and look for solutions from your head and any references. Talk to professors about the problem. Assume no specfic mode or model to follow. Ask the hard questions,[there aren't stupid questions in the class room, the work place is a different matter] like MacM.s post after my first., Look with the intensity equivalent to "lost car keys" . After a bit you mind will tell you to chill out, and it will then do all the necessary work for your best of all possible grades. The answer will not come in linear fashion with page and paragraph number., but the answer will arrive. Show that despite your revulsion re the testing system and so on, your answer will be the talk of the class. You will not leave a gravity-force uncovered. One reason for your distaste is that the probelem is a slam dunk piece of cake. It is the forced method of testing that bores you. What ever the mental dynamics of your problem solving, you do know what I am talking about, huh? One last suggestion, maybe as a footnote you can verify this angular momentum of the solar system which is 3.15 x 10^43 (kg-m)/sec^2 .The sun's conribution is 1.6 x 10^41 kg-m/m^2, but the solar system mass is 1.345 x 10^-3 of that of the sun. The sun contributes 2% of the angular momentum and 1000 times more mass. Go figure.I say AM is the real gravity. This is only a problem I can smell at the presen ttime, but I am slowly acquiring a taste if for no other reason there aren't many out there considereing research into the angular momentum scenario. Read the current post on the subject that Yuriy proposed about some extraordinary orbit problems. Actually the problem is in gyroscopic action. Very enlightening.. A PhD has answered Yuriy and has some keen insight and he writes very clearly. His forum name is BillyT. He has the remarkable ability to seem like scientist, a physicist and you can understand him. Words aren't wasted. Despite my speculative and laughable "AM scenario", reviewing the posts will be enormously beneficial. Go for it Hamsterspawn. If you were Canadian I wouldn't ask this next question, but Hamsterspawn, your identifying handle in this forum is a play on words, a double entendre, an aphorism with a sharp significance, n;cest pas? HJave you ever heard the lines in a song sung by the late rock star Jimmi Hendrix: "Scuse me while I kiss the sky". You're English , or Porteguese or something like that, aren't you? Geistkiesel
Thanks everyone, its helped a lot,maybe getting a courework grade thats better than normal will pull me back into a* in physics... wish i was as good at as chem. In response to a few questions, I am english, i did parachutes last week in physics Please Register or Log in to view the hidden image!, no ive never heard of the song, but i did have a look at the post about orbits and im keeping my eye on it.I am curious to know howcoms a guy like MacM who probably has an IQ entering a quad figure count cant spell hamster Please Register or Log in to view the hidden image! . Also, i know what you mean about boring... i sometimes wish we did something interesting that doesnt involve dropping... Youve hit the nail on the head where you say that i get bored with the method of testing, and the fact that there is virtually no work that gets done in the room except the bare minimum... I just want to learn what i need to know and go do something different and interesting with it on my terms. Ah well, thanks again... With any luck, ill look around as many posts as i can and learn a few things, maybe comeback and ask an intelligent question Please Register or Log in to view the hidden image!. Im not the best at physics, i prefer chemistry, but both i find incredibly interesting... Could someone please tell me what theoretical physics is? and Nanotechnology? i always thought that was where you broke things doen (in stupid terms) to its smallest form? i was possibly thinking about nanotechnology at uni. Thanks again guys, great help.
Oh, and i didnt understand the play on words thing? I came up with this name a few years ago when i started playing PC games, and i remember one of the first i played was Baldurs Gate 2. Well, before hand, i had watched monty python and the holy grail for about the 6th time in as many days (probably not that much, but id probably still laugh). Anyway, as im sure anyone who has watched it can recall, the frenchmen on top of the castle said 'Your mother was a hamster and your father smelt of eldeeerrrberriesh'. So, i thought about a name for myself for quite a while, and came up with hamsterspawn. Its stuck on all games ever since. Please Register or Log in to view the hidden image! Well, there you go. If you havn't seen any of the monty python films, you havn't lived... Please Register or Log in to view the hidden image! If that doesnt answer the question i give you a paragraph of irrelivant information.
Please Register or Log in to view the hidden image! It called Old Age and arthuritus. If you would I would appreciate your response to the question. Were you stating an interest in the minutia information which I posted? I thought you indicated that by your introduction. Thanks.
Pretty close. Nanotechnology is basically using individual atoms as building blocks. Standard manufacturing can only control the flow of atoms, but not individual atoms. The definition of nanotechnology has changed to include anything that is really really small, regardless of manufacturing methods. Theoretical physics is researching fundamentals. For example; researching combustion rates/products, electron flow or the energy released in biochem reactions would be theoretical physics. The information gathered isn't usually directly applicable to anything, but is a stepping stone to new technology.
Sorry MacM, i didnt quite follow you, but i think you are hinting at the older post about something very similar? (http://www.sciforums.com/showthread.php?t=39234) If so, yes, i found it very interesting. (if that isnt it, or ive made no sense, just post the question again using smaller words that i can find in a dictionary Please Register or Log in to view the hidden image!) And thanks persol, now for some improvisation. ' Pretty close. Nanotechnology is basically using individual atoms as building blocks. Standard manufacturing can only control the flow of atoms, but not individual atoms. The definition of nanotechnology has changed to include anything that is really really small, regardless of manufacturing methods. ' (originally posted by persol, sorry for copy and paste) So does this mean you could use individual atoms to make anything you wanted? If you built the atoms in a certain way, so to speak?
He's wondering whether your question was about the fraction of a nuclear radius that the earth moves toward the falling object, or whether you were actually wondering why you measured the heavier object to take less time to fall.
The end goal of nanotechnology seems to be minute chemical/machine/viruses (whatever you want to consider them) which can perform tasks. Theoretically, one of these tasks could be building objects from a molecular level. Exactly. You have different atoms which interact in specific ways when combined. Nanotechnology figures out what combination of atoms does what and, more complicate, how to put those atoms together.
He answered my question: My post was in resonse to Persol trying to implicate my information was unsought and superflous, when I clearly saw his interest in that issue in his opening post.
