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Chockeh wrote on 2010-11-15 03:05
So for my science project, I need to make a report on a experiment related to free falling (
Free fall - Wikipedia, the free encyclopedia). I'm thinking of doing something simple like taking too objects of a different weight and drop them both at the same height, which will probably fall in the same time due to Galaleo's theory. I will play around with the height to prove this true. So I assume that I should write down that the weight does not affect which object falls first, but the height does ( In scientific terms of course... once I find them out). Some of the materials I think I would be using is weights as the objects that will fall and a big ruler ( Does ones used on the blackboard ) to calculate the height of the objects. I do however, have a few problems.
1. What other materials do you suggest? Think stuff you can normally find in a lab.
2. How am I to prove that the two objects fall in the same time?
3. Feel free to suggest improvements, since I obviously don't know what I am doing.
Will ask more questions as they come into mind.
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Chillax wrote on 2010-11-15 03:22
Unless you have access to a room completely devoid of air and other matter, I don't know how you'd get a good result in your actual test. What are previous experiments that you know of and the actual words from the teacher about the assignment?
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Kueh wrote on 2010-11-15 03:31
Quote from Chillax;215747:
Unless you have access to a room completely devoid of air and other matter, I don't know how you'd get a good result in your actual test.
There's reasonable interference allowed in every lab. If every scientist talked like that, no one would ever do experiments.
@OP If by lab you mean your school's lab, try text books, stools, trashcans, anything you can pick up.
Chillax is right that you should post more info though, since there are rules there that you need to follow. A simple way to prove they fall in the same time would be to rig something that would drop the objects from the same exact height, and have two people time different objects, one if you don't have enough timers but two would be better. And you should drop them one at a time, since you're proving they take the same amount of time.
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Chockeh wrote on 2010-11-15 03:32
Yeah, my room is in space :].
In a serious note, the teacher literally just let us make up an experiment as long as it has something to do with the free fall. Some other experiments I remember has something to do with a small car, a long thing paper and something that makes dots in the paper every 0.1 seconds, so I guess it has something to do with the relation between the time and the distance... velocity?
Anyways, I really have no clue what to do, so I am willing to do any kind of experiment xD.
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Creampuff wrote on 2010-11-15 03:45
Well, going with your free fall experiment, there are a couple things that you could keep in mind that would make the demonstration more successful:
1) When Galileo performed the free fall experiment, he had to choose objects with fairly signifcant mass, so you would have to do the same in order to reduce the effects of air friction on free fall.
2) Pick objects of comparable size and shape? Spheres work well.
3) You could bring in a cool video or something to show that in a vacuum, a feather would fall at the same rate as a steel ball.
If you don't want to do free fall, I recall in high school we did a couple simple experiments related to velocity and acceleration, as well as momentum. I particularly liked the air puck table that we had. I'm not really certain what to suggest since the experiment depends on what material you have covered in your physics course.
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Lan wrote on 2010-11-15 03:47
Quote from Creampuff;215775:
Well, going with your free fall experiment, there are a couple things that you could keep in mind that would make the demonstration more successful:
1) When Galileo performed the free fall experiment, he had to choose objects with fairly signifcant mass, so you would have to do the same in order to reduce the effects of air friction on free fall.
2) Pick objects of comparable size and shape? Spheres work well.
3) You could bring in a cool video or something to show that in a vacuum, a feather would fall at the same rate as a steel ball.
If you don't want to do free fall, I recall in high school we did a couple simple experiments related to velocity and acceleration, as well as momentum. I particularly liked the air puck table that we had. I'm not really certain what to suggest since the experiment depends on what material you have covered in your physics course.
I despise that accursed air puck table -_-
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Chockeh wrote on 2010-11-15 03:53
Quote from Creampuff;215775:
Well, going with your free fall experiment, there are a couple things that you could keep in mind that would make the demonstration more successful:
1) When Galileo performed the free fall experiment, he had to choose objects with fairly signifcant mass, so you would have to do the same in order to reduce the effects of air friction on free fall.
2) Pick objects of comparable size and shape? Spheres work well.
3) You could bring in a cool video or something to show that in a vacuum, a feather would fall at the same rate as a steel ball.
If you don't want to do free fall, I recall in high school we did a couple simple experiments related to velocity and acceleration, as well as momentum. I particularly liked the air puck table that we had. I'm not really certain what to suggest since the experiment depends on what material you have covered in your physics course.
Was thinking something along the lines of these:
[Image: http://images.learningresources.com/images/products/en_us/detail/prod2065_dt.jpg]
Would that be good?
EDIT: As for material, assume we have everything a normal high school laboratory would get.
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Chihaya wrote on 2010-11-15 04:08
Air Resistance is a bish... I personally think there are many ways you can take this; it's just a matter of choosing one of them.
Just get one paper and one solid weight (made from metal) and show that density affects air resistance, which in turn affects free falling.
Is there specific factors that you need to include in your report?
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Lapitaga wrote on 2010-11-15 04:09
You could do the relationship between mass and terminal velocity (terminal velocity is the speed at which a falling object is no longer accelerating or increasing speed) At that point the force of gravity downward equals the force of air friction upward. You could tie various small weights or weighed objects to a helium ballon (which ensures that the system quickly reaches terminal velocity), and time each descent from a certain height. The heavier the object, the faster the terminal velocity.
Or to emphasize the acceleration of free fall you could drop something like a baseball from various heights, time each and then take the average speed (height/time). The higher you drop it from, the higher the average speed should be. for this you'll need to drop the ball from large, known heights or use special timing lab equipment or an accurate video camera that lets you view frame by frame and time short descents.
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Omegatronic wrote on 2010-11-15 15:05
Quote from Joyjason;215832:
Air Resistance is a bish... I personally think there are many ways you can take this; it's just a matter of choosing one of them.
Just get one paper and one solid weight (made from metal) and show that density affects air resistance, which in turn affects free falling.
Um... not to nit pick, but the density of the falling object doesn't affect terminal velocity. The only information you need about the object is drag coefficient, mass, and cross sectional area. That being said, your confusion probably derives from the use of a sphere in examples you have seen. Because it is a sphere, the drag coefficient is known. Then you would only need to know the density and radius of the sphere you can calculate the mass and cross sectional area.
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Chockeh wrote on 2010-11-15 22:54
A little update on some material I can use (Since I am translating from french, this may be a little off):
-Universal Support
-Big Ruler
-This things you need to make this (Some transmitter(?) and a special kind of paper):
[Image: http://hrsbstaff.ednet.ns.ca/mireauj/minut1_files/image002.gif]
-Weights
-Or anything I can easily buy.
Now to be more clear on the goals, like I said, this is my horrible translation from french to English:
Humans always observed natural phenomenons, one of these phenomenons is free falling. We are looking for some explications. In order to explain this phenomenon, you are going to have to discover the factors (variables) that has a key-role in free falling and you are also going to have to discover what relations are happening during a free-fall. To do this, you are going to have to experiment on your own.
So what I did for now without much though is that I took a weight of 500g and a weight of 1000g, attached it to the paper, open the machine (Whatever its called) and let go of the weight. So my papers has plenty of dots which tells the distance and time of the fall of each weight. Not sure what exact;y I can do with these yet, though I can always start a new experiment at the moment. Also, I don't have any super video camera :[.
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JustNoOne wrote on 2010-11-15 23:59
Since you have to discover factors affect freefall, I won't tell you any factors, but you're on the right track.
The machine you attach the paper to is probably called a ticker-tape timer, the paper is respectively called a ticker-tape-timer tape; these were used long ago to measure distance from one dot to another, velocity and acceleration. Those machines should make dots every 1/60th of a second and I'll leave it there =P
Also measure the distances between each dot =P
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Chockeh wrote on 2010-11-16 00:09
Quote from JustNoOne;216583:
Since you have to discover factors affect freefall, I won't tell you any factors, but you're on the right track.
The machine you attach the paper to is probably called a ticker-tape timer, the paper is respectively called a ticker-tape-timer tape; these were used long ago to measure distance from one dot to another, velocity and acceleration. Those machines should make dots every 1/60th of a second and I'll leave it there =P
Also measure the distances between each dot =P
What I do know is that every dot equals 0.1 second so 6 dots is 1 second and that each dot is a postion ( So we can easily find out the distance). With that I can find out what the Velocity and the Acceleration is. As for a shortcut, I am not sure but... does a=2 â–³S / â–³t^2 where â–³S is the position and â–³t is the time. Now then, I just lost myself again :D.
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JustNoOne wrote on 2010-11-16 00:22
Sadly no, but you are close ^^ The only thing I don't understand is what "position" means? Is it the distance from the first dot recorded to another dot or is it a dot you choose yourself? In both cases, that's not the right equation Dx
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Chockeh wrote on 2010-11-16 00:29
Quote from JustNoOne;216600:
Sadly no, but you are close ^^ The only thing I don't understand is what "position" means? Is it the distance from the first dot recorded to another dot or is it a dot you choose yourself? In both cases, that's not the right equation Dx
It's the position it is from dot 0.
Well, I do go to a french school so the translations might be off.
But yeah, position is basically distance.
Weird, always though a=2â–³s/â–³t^2 when the initial velocity is 0.