Cursed Gravity
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I appear to have a hole in my understanding of basic physics. A hammer and a feather fall at the same rate on the moon. (I think they actually did this). But bearing in mind force is equal to mass times acceleration. Gravity is a constant force but the mass of a hammer is much greater than that of a feather, so acceleration should be different? It seems gravity ignores mass when it accelerates things. What's going on? Can someone please explain the painfully stupid thing I'm missing so I can get on with the day? I blame last night's Prosecco for this mental lapse.
Regards, Rob Philpott.
Um, you multiply the mass by the acceleration to get the force, so it's the force that changes if the mass or acceleration change. Changing the mass doesn't change the acceleration, and changing the acceleration doesn't change the mass.
I wanna be a eunuchs developer! Pass me a bread knife!
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I appear to have a hole in my understanding of basic physics. A hammer and a feather fall at the same rate on the moon. (I think they actually did this). But bearing in mind force is equal to mass times acceleration. Gravity is a constant force but the mass of a hammer is much greater than that of a feather, so acceleration should be different? It seems gravity ignores mass when it accelerates things. What's going on? Can someone please explain the painfully stupid thing I'm missing so I can get on with the day? I blame last night's Prosecco for this mental lapse.
Regards, Rob Philpott.
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I appear to have a hole in my understanding of basic physics. A hammer and a feather fall at the same rate on the moon. (I think they actually did this). But bearing in mind force is equal to mass times acceleration. Gravity is a constant force but the mass of a hammer is much greater than that of a feather, so acceleration should be different? It seems gravity ignores mass when it accelerates things. What's going on? Can someone please explain the painfully stupid thing I'm missing so I can get on with the day? I blame last night's Prosecco for this mental lapse.
Regards, Rob Philpott.
Firstly, mass has a gravitational effect. It bends space time, so the more mass something has, the more it bends. From this is can extrapolated that the hammer hits the ground before the feather. Basic physics my friend. It is just a shame they do not actually teach this, and merely spout the same crapola about them landing at the same time. However... If a hammer is dropped from 10 metres and the time to impact is recorded, and the feather is dropped from 10 metres and the time recorded they will appear to be the same. This is because the mass differential between the hammer and the feather is so slight as to be negligible. No-one believe me? Here is a mind experiment. The hammer and the feather are both at 10 metres above the ground. HOWEVER, they are at opposite sides of the moon. Now the moon will pull upon them both, causing them to fall. And this is where it becomes obvious... The hammer has a mass that is pulling the moon, ever so slightly, toward it. The feather has a mass that is pulling the moon too, but as the mass of the hammer is greater, the moon will move toward it. This means that the hammer has less distance to fall, and the feather more. Therefore, if dropped at the same time, the hammer hits first. QED
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
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Um, you multiply the mass by the acceleration to get the force, so it's the force that changes if the mass or acceleration change. Changing the mass doesn't change the acceleration, and changing the acceleration doesn't change the mass.
I wanna be a eunuchs developer! Pass me a bread knife!
or divide the force by the mass to get the acceleration.
Mark_Wallace wrote:
Changing the mass doesn't change the acceleration, and changing the acceleration doesn't change the mass.
It does when the force is constant.
Regards, Rob Philpott.
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Um, you multiply the mass by the acceleration to get the force, so it's the force that changes if the mass or acceleration change. Changing the mass doesn't change the acceleration, and changing the acceleration doesn't change the mass.
I wanna be a eunuchs developer! Pass me a bread knife!
Mass increases as a function of velocity though. (Not the real mass, but the relativistic mass) Read Lev Okun for a view in this matter.
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
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Um, you multiply the mass by the acceleration to get the force, so it's the force that changes if the mass or acceleration change. Changing the mass doesn't change the acceleration, and changing the acceleration doesn't change the mass.
I wanna be a eunuchs developer! Pass me a bread knife!
Mark_Wallace wrote:
Changing the mass doesn't change the acceleration
Beg to differ, it is why sports car manufacturers strive to lighten the vehicles. F=ma, or, a=F/m ergo, reduce mass, increase acceleration where the force is constant.
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
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Firstly, mass has a gravitational effect. It bends space time, so the more mass something has, the more it bends. From this is can extrapolated that the hammer hits the ground before the feather. Basic physics my friend. It is just a shame they do not actually teach this, and merely spout the same crapola about them landing at the same time. However... If a hammer is dropped from 10 metres and the time to impact is recorded, and the feather is dropped from 10 metres and the time recorded they will appear to be the same. This is because the mass differential between the hammer and the feather is so slight as to be negligible. No-one believe me? Here is a mind experiment. The hammer and the feather are both at 10 metres above the ground. HOWEVER, they are at opposite sides of the moon. Now the moon will pull upon them both, causing them to fall. And this is where it becomes obvious... The hammer has a mass that is pulling the moon, ever so slightly, toward it. The feather has a mass that is pulling the moon too, but as the mass of the hammer is greater, the moon will move toward it. This means that the hammer has less distance to fall, and the feather more. Therefore, if dropped at the same time, the hammer hits first. QED
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
So the answer is really it depends!!! But what if, there was a satellite flying over the feather? It will also pull the moon, ever so slightly, towards itself! It might spoil the result!!
My programming get away... The Blog... DirectX for WinRT/C# since 2013! Taking over the world since 1371!
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Firstly, mass has a gravitational effect. It bends space time, so the more mass something has, the more it bends. From this is can extrapolated that the hammer hits the ground before the feather. Basic physics my friend. It is just a shame they do not actually teach this, and merely spout the same crapola about them landing at the same time. However... If a hammer is dropped from 10 metres and the time to impact is recorded, and the feather is dropped from 10 metres and the time recorded they will appear to be the same. This is because the mass differential between the hammer and the feather is so slight as to be negligible. No-one believe me? Here is a mind experiment. The hammer and the feather are both at 10 metres above the ground. HOWEVER, they are at opposite sides of the moon. Now the moon will pull upon them both, causing them to fall. And this is where it becomes obvious... The hammer has a mass that is pulling the moon, ever so slightly, toward it. The feather has a mass that is pulling the moon too, but as the mass of the hammer is greater, the moon will move toward it. This means that the hammer has less distance to fall, and the feather more. Therefore, if dropped at the same time, the hammer hits first. QED
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
Nice point, and an interesting twist to the story.
Regards, Rob Philpott.
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Mark_Wallace wrote:
Changing the mass doesn't change the acceleration
Beg to differ, it is why sports car manufacturers strive to lighten the vehicles. F=ma, or, a=F/m ergo, reduce mass, increase acceleration where the force is constant.
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
But isn't the resisting force here air friction, and not gravity?
Sarchasm : The gulf between the author of sarcastic wit and the person who doesn't get it.
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Firstly, mass has a gravitational effect. It bends space time, so the more mass something has, the more it bends. From this is can extrapolated that the hammer hits the ground before the feather. Basic physics my friend. It is just a shame they do not actually teach this, and merely spout the same crapola about them landing at the same time. However... If a hammer is dropped from 10 metres and the time to impact is recorded, and the feather is dropped from 10 metres and the time recorded they will appear to be the same. This is because the mass differential between the hammer and the feather is so slight as to be negligible. No-one believe me? Here is a mind experiment. The hammer and the feather are both at 10 metres above the ground. HOWEVER, they are at opposite sides of the moon. Now the moon will pull upon them both, causing them to fall. And this is where it becomes obvious... The hammer has a mass that is pulling the moon, ever so slightly, toward it. The feather has a mass that is pulling the moon too, but as the mass of the hammer is greater, the moon will move toward it. This means that the hammer has less distance to fall, and the feather more. Therefore, if dropped at the same time, the hammer hits first. QED
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
Not necessarily so: the mass of the hammer will also attract the feather...
The universe is composed of electrons, neutrons, protons and......morons. (ThePhantomUpvoter)
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But isn't the resisting force here air friction, and not gravity?
Sarchasm : The gulf between the author of sarcastic wit and the person who doesn't get it.
So? Force is Force, regardless. It is the maths that is important. (It is also why sports cars are sexily sleek) At high speeds (above 120 or so) the air gets so thick it is actually difficult to get through. (This is the terminal velocity for skydivers, the thickness of the air inhibits further acceleration).
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
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Not necessarily so: the mass of the hammer will also attract the feather...
The universe is composed of electrons, neutrons, protons and......morons. (ThePhantomUpvoter)
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So? Force is Force, regardless. It is the maths that is important. (It is also why sports cars are sexily sleek) At high speeds (above 120 or so) the air gets so thick it is actually difficult to get through. (This is the terminal velocity for skydivers, the thickness of the air inhibits further acceleration).
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
Isn't this a thread about gravity?! ;)
Sarchasm : The gulf between the author of sarcastic wit and the person who doesn't get it.
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Isn't this a thread about gravity?! ;)
Sarchasm : The gulf between the author of sarcastic wit and the person who doesn't get it.
I think you have lost sight of the gravity of the situation.
The universe is composed of electrons, neutrons, protons and......morons. (ThePhantomUpvoter)
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Isn't this a thread about gravity?! ;)
Sarchasm : The gulf between the author of sarcastic wit and the person who doesn't get it.
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I appear to have a hole in my understanding of basic physics. A hammer and a feather fall at the same rate on the moon. (I think they actually did this). But bearing in mind force is equal to mass times acceleration. Gravity is a constant force but the mass of a hammer is much greater than that of a feather, so acceleration should be different? It seems gravity ignores mass when it accelerates things. What's going on? Can someone please explain the painfully stupid thing I'm missing so I can get on with the day? I blame last night's Prosecco for this mental lapse.
Regards, Rob Philpott.
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Wow, reading this line of posts makes me want to be drunk just now. Much more fun when done at midnight on a Friday when everyone will think they're right.
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I appear to have a hole in my understanding of basic physics. A hammer and a feather fall at the same rate on the moon. (I think they actually did this). But bearing in mind force is equal to mass times acceleration. Gravity is a constant force but the mass of a hammer is much greater than that of a feather, so acceleration should be different? It seems gravity ignores mass when it accelerates things. What's going on? Can someone please explain the painfully stupid thing I'm missing so I can get on with the day? I blame last night's Prosecco for this mental lapse.
Regards, Rob Philpott.
Rob Philpott wrote:
It seems gravity ignores mass when it accelerates things. What's going on?
Gravity does not discriminate against fat people. ;P
"Bastards encourage idiots to use Oracle Forms, Web Forms, Access and a number of other dinky web publishing tolls.", Mycroft Holmes[^]
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Firstly, mass has a gravitational effect. It bends space time, so the more mass something has, the more it bends. From this is can extrapolated that the hammer hits the ground before the feather. Basic physics my friend. It is just a shame they do not actually teach this, and merely spout the same crapola about them landing at the same time. However... If a hammer is dropped from 10 metres and the time to impact is recorded, and the feather is dropped from 10 metres and the time recorded they will appear to be the same. This is because the mass differential between the hammer and the feather is so slight as to be negligible. No-one believe me? Here is a mind experiment. The hammer and the feather are both at 10 metres above the ground. HOWEVER, they are at opposite sides of the moon. Now the moon will pull upon them both, causing them to fall. And this is where it becomes obvious... The hammer has a mass that is pulling the moon, ever so slightly, toward it. The feather has a mass that is pulling the moon too, but as the mass of the hammer is greater, the moon will move toward it. This means that the hammer has less distance to fall, and the feather more. Therefore, if dropped at the same time, the hammer hits first. QED
--------------------------------- I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC Link[^]
It's just a shame nobody has been to the moon to try out the experiment...
MVVM# - See how I did MVVM my way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
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or divide the force by the mass to get the acceleration.
Mark_Wallace wrote:
Changing the mass doesn't change the acceleration, and changing the acceleration doesn't change the mass.
It does when the force is constant.
Regards, Rob Philpott.
This isn't a pure Mathematics calculation, where any number can be varied. The velocities, in this case, are purely calculated values, which are derived from the values of properties of the hammer, the feather, any forces applied, and any frictional effects. Those don't change, and there is no way of unilaterally changing the value of the velocity derived from them. You can't just declare "I've decided that the velocity is twice as much when it's the hammer!", and expect the hammer to break the laws of Physics to meet the requirements of your declaration. There's a big line between Mathematical possibility and the practical application of Maths.
I wanna be a eunuchs developer! Pass me a bread knife!
