garublador
* Ace Member *
Incorrect. Gravity is directly proportional to mass. That's why there's less gravity on the moon than there is on Earth. The moon has less mass. Less mass means a smaller gravitational force.
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How do you get 500+ throws??????
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toothyfish
* Ace Member *
Now if we realy want to get technical, gravity does not exert a force on the airplane. It is trying to accelerate the airplance downward. The result is a force, exerted against the air, which is exerting a force upward. When these two are equal, we have a plane that can fly.
Gravity isn't directly proportional to anything but its distance away from the center of the massive rotating object that it's being pulled toward... our case, earth. The object on the moon (edit: the moon being of smaller mass creates less gravitational force) is farther away from the center of the earth than I am currently and is being pulled toward earth less. At our distance from the earth there is the same gravitational force pulling ALL objects towards the center of earth. That is the gravitational constant, it doesn't change for different objects
lol, And we totally hijacked this thread, my bad...
lol, And we totally hijacked this thread, my bad...
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toothyfish
* Ace Member *
So the key to 500ft plus throws is go to the moon! Oh, that won't work, there's no air to create the lift!
I forgot to mention lift. Lift is produced when the air passing over the top of an object travels more distance than the air passing below the object. This creates a pressure difference between the top and bottom of the object and thus an upward force. The force opposes the force of gravity and slows it's downward acceleration, causing the object to stay in the air longer.
garublador
* Ace Member *
The gravitational constand doesn't change, but the force caused by gravity depends on the mass of both objects.
F = GmM/(r^2)
Where:
F = force caused by gravity
G = gravitational constant
m = mass of the first object
M = mass of the second object
r = distance between the objects
The Earth is one mass and the disc is another. If the mass of the disc changes the force from gravity changes.
That's OK, there can't be more than a person or two on here who really knows how to extend distance at that range anyway.
toothyfish
* Ace Member *
By time we're done here, I'll be ready to take the PE exam.
garublador
* Ace Member *
I wonder if we've done the "Airplane on a conveyor" thread here yet...
toothyfish
* Ace Member *
Care to lead us off? Sounds like relative velocity...I feel some good movie quotes about to come out...
True, but as I stated previously, the difference in the force of gravity acting on say a 150g disc and a 180g disc is so small it is essentially zero. It would be like the difference between a decimal point with 1000 zeroes followed by a 1 vs a decimal point with 999 zeroes followed by a 1. For all practical purposes they are the same.
Did you mean Terminal Velocity?
garublador
* Ace Member *
The magnitude of the difference between discs of different weights has never been relavant to this discussion. The fact that there is a difference, on the other hand, is what we are discussing.
mambrose
Double Eagle Member
i honestly think a 170 ESP crush thats just a little worn in gets you 500 foot
toothyfish
* Ace Member *
We're not using the same meaning of the word force. Force is a weight, in Newtons. Grams is a unit of mass that we use to mean wieght, incorrectly by science and physics, but we do it anyway. I think the confusion is that we may be thinking that gravity is "pushing" down on the disc with a force. That's the perception, but not quite how it works mathematically.
The full formula of F = GmM/(r^2) is the right one, but it is summarized by F=ma, where m is the mass of the object and a is the accelaration, which in this case is g, the accelration due to gravity.
So using F=mg, where g=9.81 m/s^2, that way I don't have to look up the mass of the earth and G, since 9.81 blah came from this. (or vice versa)
If a disc's mass is 150g that is .15 kg. So .15 kg * 9.81 m/s^2 = 1.4715 N. THis is it's weight and also the force which it exerts on the earth if it is laying on the ground. It is also the force of lift required to hold it in the air. Agreed?
So if a disc's mass is 180g, that's .18 kg. So .18 kg * 9.81 blah = 1.7658 N . This is this disc's weight and also the force of lift required to hold it in the air.
The 180g disc requires much more lift to keep it in the air. 180/150= 1.2
20% more lift is required to "levitate" this disc. Now how that translates into velocity, I don't know but lift requires pressure differential, so a greater pressure differential is required t lift the heavy disc, which comes from higher speed/spin, because both discs have the same surface area. It's a function of the lift coeffieceint, which would be the same for a given form or shape. But it's the same for a given model of disc.
I'm done, thank you for this review...have a good weekend, forget physics, and go play disc golf...
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We're not using the same meaning of the word force. Force is a weight, in Newtons. Grams is a unit of mass that we use to mean wieght, incorrectly by science and physics, but we do it anyway. I think the confusion is that we may be thinking that gravity is "pushing" down on the disc with a force. That's the perception, but not quite how it works mathematically.
The full formula of F = GmM/(r^2) is the right one, but it is summarized by F=ma, where m is the mass of the object and a is the accelaration, which in this case is g, the accelration due to gravity.
So using F=mg, where g=9.81 m/s^2, that way I don't have to look up the mass of the earth and G, since 9.81 blah came from this. (or vice versa)
If a disc's mass is 150g that is .15 kg. So .15 kg * 9.81 m/s^2 = 1.4715 N. THis is it's weight and also the force which it exerts on the earth if it is laying on the ground. It is also the force of lift required to hold it in the air. Agreed?
So if a disc's mass is 180g, that's .18 kg. So .18 kg * 9.81 blah = 1.7658 N . This is this disc's weight and also the force of lift required to hold it in the air.
The 180g disc requires much more lift to keep it in the air. 180/150= 1.2
20% more lift is required to "levitate" this disc. Now how that translates into velocity, I don't know but lift requires pressure differential, so a greater pressure differential is required t lift the heavy disc, which comes from higher speed/spin, because both discs have the same surface area. It's a function of the lift coeffieceint, which would be the same for a given form or shape. But it's the same for a given model of disc.
I'm done, thank you for this review...have a good weekend, forget physics, and go play disc golf...
I agree with most of what you are saying. Yes there is some confusion here about what we mean by force. We are actually talking about several forces here.
1. Force of gravity- The attractive force that exists between any two objects, in this case the earth and a disc.
2. Lift force- Upward force acting on a disc due to pressure differences between the two surfaces.
3. Weight of the disc- mass of disc X g (9.8m/s)
There are more, but I'll stop here.
All I am trying to say is that the mass of the disc doesn't affect how gravity acts on it. I am not saying that lighter discs won't fly farther than heavy ones. But that has nothing to do with gravity. It has to do with lift forces and wind resistance. Lift forces do affect lighter discs more than heavier ones.
toothyfish
* Ace Member *
Number 1 and number 3 are the same thing. We're not talking about two celestail bodies, like the earth and moon. Force due to gravity and weight (not mass) are indeed the same. If I go to the moon, my mass remains the same, but my weight will be much less, one sixth if I remember correctly because the gravitational pull of the moon is one-sixth of that of the earth. Doesn't change the fact that I'm getting fatter. Same mass. Same a$$. Different reading on the scale.
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I agree that in the case of gravity between the earth and a disc the two terms are pretty much the same. In the previous posts we were talking about the universal law of gravitation which is not always the same thing.
And yes, we definitely hijacked this thing.
Now that I've made a complete nerd out of myself, I'm gonna have to go change my user name.
getting back to the original topic. If I want 500+ feet I throw my disc twice. LOL
815PowerBoss
Newbie
That's interesting that Sweden uses feet to measure instead of meters...Anyway
First of if you are throwing over 450 consistently you don't need to focus on 500+ most people would love to get 400.
secondly disc distance is basically physics, which you should be learning about in high school soon. You have a few years of growth still, as you grow, your arms will get longer and naturally increase your distance. Force X Distance, you will be able to put force on the disc for longer. Plus you arm being longer and you being taller will increase the lever arm action and height of release.
so basically all you have to do is...get an A in physics and keep growing up
I thought the same about the non use of the metric system. Maybe he tried to convert and didn't carry the one?
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