As many as you can get to come home to roost! Usually all of them.🙂
Wasn't Isaac a scholar? Although that doesn't mean he had anything better to do than eat cake and daydream. However with a quill, it did take him some time.
Wasn't Isaac a scholar? Although that doesn't mean he had anything better to do than eat cake and daydream. However with a quill, it did take him some time.
Let's get that straight!
Not only did Newton not "invent" gravity, he didn't even try to explain it!
What he did was to come up with the 'Law of Universal Gravitation' - the formula by which the force of gravitational attraction between any two objects can be calculated.
And, the apple story is simply a fairy tale!
Did an apple actually fall on Newton's head?
Did an apple really fall on Isaac Newton’s head? - HISTORY
Did an apple really fall on Isaac Newton’s head? - HISTORY
I don't know about the Isaac's Apple, I was not born.
I like the Cavendish experiment that measured G, because that is a direct use of the Newton's law and it is damn sensitive with clever refinements.
Cavendish experiment - Wikipedia
I like the Cavendish experiment that measured G, because that is a direct use of the Newton's law and it is damn sensitive with clever refinements.
Cavendish experiment - Wikipedia
NASA has tested a methane engine that could be used for Mars landers, rather than for the journey from Earth to Mars.
NASA Tests Methane Engine Components for Next Generation Landers | NASA
SpaceX has been developing methane engines for their Raptor rocket programme.
SpaceX Raptor - Wikipedia
It is easy for the layman to think, mistakenly, that gravity is a 'one way' force i.e. that the Earth just attracts you (or an apple!).
However, not only does the Earth attract you, but you attract the Earth with an equal and opposite force. When an 80 kg man jumps off a wall, the Earth attracts him downwards with a force of almost 800N. At the same time, the man attracts the Earth upwards with a force of 800N. Of course, we don't see the Earth accelerate towards the man because of its immense mass.
In fact, all objects attract each other because of gravity. Even the pen and pencil on your desk attract each other, only we don't see them move together since gravity is weak when the masses are small. The force of friction on the surface of the desk easily prevents the pen and pencil moving together under the effect of their mutual gravitational attraction.
Newton's genius lay in realising that gravity is a MUTUAL interaction between any two objects in the universe. No one had come up with that concept prior to Newton.
The Cavendish balance is so sensitive that it can measure the tiny force of gravitational atraction between two spheres of everyday mass. By measuring the angle of twist of a supporting torsion wire, the magnitude of the gravitational forces can be calculated.
Cavendish's torsion-bar experiment HD - YouTube
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My understanding of Newton's Law of Gravity is what goes up comes down! 😀
Classic example by Elon Musk's SpaceX here:
Up in flames: SpaceX Starship test flight ends in fiery crash, again | SpaceX | The Guardian
Who could not call that a disaster? 😱
Second shot at getting Starship to work. Frankly I've seen enough. Hopeless idea.
I say this as a man who designed low-budget Space-rockets in my youth. They didn't go far, but worked 2 times out of 3. 😎
Classic example by Elon Musk's SpaceX here:
Up in flames: SpaceX Starship test flight ends in fiery crash, again | SpaceX | The Guardian
Who could not call that a disaster? 😱
Second shot at getting Starship to work. Frankly I've seen enough. Hopeless idea.
I say this as a man who designed low-budget Space-rockets in my youth. They didn't go far, but worked 2 times out of 3. 😎
He was more than that, he was a genius!
No one prior to him had considered that the apple was attracting the Earth.
What!! Why am I just learning this now??? They never taught us gravity is mutual! Okay now I'm pissed off. I find that incredibly amazing. But how could it be the same from both sides? Doesn't the force of gravity increase with mass?
Let's have a confession by all who are just learning this now 🙂
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What happened to your selective quoting skills, Pete?
Newton told us that the mutual force of gravitational attraction increases as the product of the masses increases i.e. in proportion to M x m.
Hence, only one of the masses has to increase to increase the mutual force of gravity.
(In the case of the apple, M is the mass of the Earth while m is the mass of the apple.)
Indeed, this was not point at when we were taught gravity.
However, it is clearly written in
F = G Mm/d^2
A 0.1 kg apple falling is attracted by the Earth by a 1 Newton force, so far so good.
How come this apple attracts the Earth by a 1N force.
Actually it attracts every bit of the earth by a tiny force, some of these bits are far away, in Hawaii New Caledonia, New Zealand, some down near the Earth center. The important point is, that there are an enormous amount of these bits. When you sum all these tiny forces over all the bits that make the Earth, you do get 1Newton.
This can be proved by a triple integral over the said bits. Such maths prove, the attraction is the same as if the total mass was in the center of the Earth.
However, it is clearly written in
F = G Mm/d^2
A 0.1 kg apple falling is attracted by the Earth by a 1 Newton force, so far so good.
How come this apple attracts the Earth by a 1N force.
Actually it attracts every bit of the earth by a tiny force, some of these bits are far away, in Hawaii New Caledonia, New Zealand, some down near the Earth center. The important point is, that there are an enormous amount of these bits. When you sum all these tiny forces over all the bits that make the Earth, you do get 1Newton.
This can be proved by a triple integral over the said bits. Such maths prove, the attraction is the same as if the total mass was in the center of the Earth.
Perhaps you don't quite understand the significance of the word 'mutual'.
Mutual means common to both masses i.e. each mass must experience the same (but opposite) force.
Yes, for the purposes of gravitational calculations, we can simply make the simplification that all of the mass of a planet resides at its centre.
Hah!
I did phrase that to induce some controversy 😀
Nice to see it triggered a bit of response.
The point was that it's becoming increasingly difficult to come up with new and relevant theories that are actually useful. I'll go out on a limb and say that someone like Archimedes has brought much more to the world of Science than Isaac Newton did, but none of them will find their equal in the modern world simply because the modern Science relies a lot on the work of previous generations, and looking at the works of Archimedes and Newton amongst others, they've made a brilliant foundation.
The world is different, people do not have the isolation, time or money to think by themselves anymore.
Sure, happens seemingly all the time. Some of the more known classic examples are summarized here:
Three Failures of Classical Physics
It's not uncommon that some theory attracts attention, a lot of time is spent trying to prove it's real, sometimes a lot of effort, time, resources and pride are put into proving that particular theory. The increasing amount of effort, time, resources and pride invested make it increasingly more valuable to "prove" that particular theory as something relevant and important to further bring the Science along. It may not be for decades or even centuries after that some of the things done today can be discredited as chasing rainbows and replaced with the actual "goings on" of the universe. The only things we see from our perspective is that on which theories that have "won", after all history is written on the basis of Victors, never the ones who lost.
Still quite interested in the amount of chickens needed to make enough methane 😀
Especially so since people have done serious maths and physics simulations on how much slappin' a chicken needs to get cooked.
How Many Slaps does it Take to Cook a Chicken? - YouTube
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