Quizzes & Puzzles9 mins ago
Gravity
Can anyone explain to me (in laymens terms) exactly what gravity is?
I dont want links to websites explaining it as Ive looked at those and cant make head nor tail of them. I just want a simple explanation why things fall down and not up.
Why does the earth keep the moon in orbit? Apparently the more matter the more gravity right? So why cant I orbit a frozen pea around a football? Come to that, why hasnt the moon fallen to earth yet?
Dont expect I'll wrap my head around it but humour me anyway.
I dont want links to websites explaining it as Ive looked at those and cant make head nor tail of them. I just want a simple explanation why things fall down and not up.
Why does the earth keep the moon in orbit? Apparently the more matter the more gravity right? So why cant I orbit a frozen pea around a football? Come to that, why hasnt the moon fallen to earth yet?
Dont expect I'll wrap my head around it but humour me anyway.
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This video is said to be 'the simplest explanation yet' ! of why Gravity makes things fall down
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I can't do better
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I can't do better
Well , i've just googled ' what is gravity '
One of the 'explanations ' started off thus -
All of us know the effects of the mysterious force called gravity. However, the question 'what is gravity' is not easy to answer at all. The reason is that we don't really understand what this force actually is (if it is a force at all)
One of the 'explanations ' started off thus -
All of us know the effects of the mysterious force called gravity. However, the question 'what is gravity' is not easy to answer at all. The reason is that we don't really understand what this force actually is (if it is a force at all)
I hope the following is helpful:
"Why can't I orbit a frozen pea around a football?"
The catch about gravity is that it's weak. Seriously weak. Stupidly weak. This means that, while there is a force of gravity between the pea and the football, it's completely dominated by any other forces involved.
You can convince yourself that gravity is stupidly weak by the simple experiment of standing up. That's your tiny body pushing against the combined gravity of the entire earth. And you win with very little effort (although good luck doing the same thing on Jupiter).
"Why does the earth keep the moon in orbit? ... Come to that, why hasn't the moon fallen to earth yet?"
Remarkably, the Moon is actually slipping out of Earth's grasp, rather than falling in. Again, this is associated partly with how weak Gravity is. The effective force that's making the Moon want to leave (this is centrifugal force, due to the Moon's orbit) is stronger than Gravity that's keeping it in. If the Moon weren't orbiting the Earth it probably would have fallen in long, long ago, but rather like satellites, once you get them orbiting at the right speed they stay in orbit.
"Apparently the more matter the more gravity right?"
Yes. All other things being equal, the more mass an object has the greater its gravity. In many cases, the dominant part of the equation is distance between two objects, so that if they are far enough apart, all the matter in the world won't make much difference.
"I just want a simple explanation why things fall down and not up."
Gravity is an attractive force, so that things can only ever move towards each other under the influence of gravity (if there were such as thing as "negative mass" then this would not longer be true. But there isn't so it is
.) And then, you may as well define "down" as "the direction gravity takes you relative to an object". It's a bit of a circular definition but that can't be helped.
"Can anyone explain...what gravity is?"
No, afraid not. Nobody knows yet!
"Why can't I orbit a frozen pea around a football?"
The catch about gravity is that it's weak. Seriously weak. Stupidly weak. This means that, while there is a force of gravity between the pea and the football, it's completely dominated by any other forces involved.
You can convince yourself that gravity is stupidly weak by the simple experiment of standing up. That's your tiny body pushing against the combined gravity of the entire earth. And you win with very little effort (although good luck doing the same thing on Jupiter).
"Why does the earth keep the moon in orbit? ... Come to that, why hasn't the moon fallen to earth yet?"
Remarkably, the Moon is actually slipping out of Earth's grasp, rather than falling in. Again, this is associated partly with how weak Gravity is. The effective force that's making the Moon want to leave (this is centrifugal force, due to the Moon's orbit) is stronger than Gravity that's keeping it in. If the Moon weren't orbiting the Earth it probably would have fallen in long, long ago, but rather like satellites, once you get them orbiting at the right speed they stay in orbit.
"Apparently the more matter the more gravity right?"
Yes. All other things being equal, the more mass an object has the greater its gravity. In many cases, the dominant part of the equation is distance between two objects, so that if they are far enough apart, all the matter in the world won't make much difference.
"I just want a simple explanation why things fall down and not up."
Gravity is an attractive force, so that things can only ever move towards each other under the influence of gravity (if there were such as thing as "negative mass" then this would not longer be true. But there isn't so it is
.) And then, you may as well define "down" as "the direction gravity takes you relative to an object". It's a bit of a circular definition but that can't be helped.
"Can anyone explain...what gravity is?"
No, afraid not. Nobody knows yet!
It's possible to expand a bit on what gravity might be. Essentially, there are two main ideas: Either gravity is just an accident, a result of how you define where you are in the Universe (this basically is the "gravity is geometry" idea); or gravity is the force that is carried by particles called gravitons (that are basically the same as photons that carry the force of electricity). This last is the answer that's implied by String Theory, SuperGravity, Quantum Gravity, etc etc... and in one form or the other is likely to be the correct one.
I reckon at the right velocity and distance, in the vacuum of space, you could orbit a pea around a football, if you could get the football to not explode that is.
If you try it on Earth, Earth's gravity will override what you're trying to do because its mass is greater than either the pea or the football.
If you try it on Earth, Earth's gravity will override what you're trying to do because its mass is greater than either the pea or the football.
So, we send a box of fluffy kittens up into space (wearing kitten spacesuits of course).
They are weightless in space, but their mass is the same because there are still the same amount of kittens of the same size as when they were on Earth (including the tiny spacesuits of course).
Weight varies, mass doesn't, unless something is added or taken away (like the tiny spacesuits BUWAHAHAH!).
They are weightless in space, but their mass is the same because there are still the same amount of kittens of the same size as when they were on Earth (including the tiny spacesuits of course).
Weight varies, mass doesn't, unless something is added or taken away (like the tiny spacesuits BUWAHAHAH!).
