accelleration of gravity

[Gaston]

is the accelleration of gravity the same anywhere in the universe or does it depend on the mass of the object that is creating the gravity?

 

[Leftyretro]

is the accelleration of gravity the same anywhere in the universe or does it depend on the mass of the object that is creating the gravity?

The latter, have you ever heard of black holes?

Lefty

 

[Gaston]

i know a black hole has more gravity due to its density i didn't know if the acceleration was different. in other words is the gravitational constant i used in physics only good on earth? is there another constant for lets sat the moon?

 

[Gayan Soyza]

I wonder why only the SMOKE goes up that not effecting the gravity.

I asked because when I'm soldering all the smoke comes to my face if that force by the gravity all smoke will go down.but its the other way.

 

[Sceadwian]

The gravitational constant is actually an equation. It is different everywhere, even on earth there are local gravity distortions due to density variations in the earths crust. If you look up Gravitational constant in wikipedia it might help to clarify.

 

[mneary]

I wonder why only the SMOKE goes up that not effecting the gravity.

Smoke goes up because the higher temperature creates a lighter packet of air which rises. (Relative to cooler air.) The particles which make it 'smoke' don't matter much.

 

[Broz]

is the accelleration of gravity the same anywhere in the universe or does it depend on the mass of the object that is creating the gravity?

The acceleration due to gravity depends on the force between the two objects. That force depends on the mass of the two objects and the distance between them. Here on Earth, the acceleration due to gravity is 9.8 m/s^2. Though, it is slightly variable depending on how far from the center of the Earth you are. If you like equations we have:

Newton's Second Law: F = m*a which can be rearranged for acceleration a = F/m. So the acceleration of an object is the force acting on the object divided by it's mass.

If the force acting on the object is gravity then by Newton's law of gravitation we have F = G*(M*m/r^2) where M is the mass of the first object, m is the mass of the second object, r is the distance between them, and G is the universal gravitational constant. As far as we know, G is the same everywhere, hence the universal part, and it doesn't change, hence the constant part.

If you plug this into a = F/m then we have a = G*M/r^2. Notice the mass of the second object disappears and this is why it is said that all objects on Earth accelerate at the same rate regardless of their mass. This is true if we are only talking about acceleration near the surface. This is because we have that r^2 in the denominator. So as we move further from the center of the Earth, the acceleration will actually decrease. For most practical applications though, any calculations done within the atmosphere can use the acceleration of 9.8 m/s^2.

Also notice that if you are on the moon, then M is different, and so the acceleration due to gravity is different on the moon than on Earth.

 

[dknguyen]

Gravity is the attractive force of an object by virtue of it's mass. Since objects have different masses, different objects have different forces of gravity, and since the forces are different, the accelerations must also be different (between different sources)...but...THe thing about gravity, though, is that the force applied scales up with the target object's mass, so the acceleration of different masses towards the body is the same. So although the acceleration of gravity varies with different sources, the acceleration remains constant for bodies being attracted by that source, regardless of their mass.

THen there's all that mumbo jumbo about everything being a source and a target object.

 

[Gaston]

thanks guys, that answered my question
i was wondering why when watching men walking on the moon;they looked like they would fall back to the surface in slow motion. especialy with no atmosphere. but if the acceleration is lower that explains it. while we are on the subject...do you guys believe man has really gone to the moon?

 

[things]

Smoke goes up because the higher temperature creates a lighter packet of air which rises. (Relative to cooler air.) The particles which make it 'smoke' don't matter much.

beat me too it mneary! , even though i think it was a retoricle question

 

[Oznog]

While we have observed the gravitational constant to be just that- a constant- and it has largely been proven to be true for celestial bodies, it's worthwhile to note that we haven't proven it's always true anywhere in the universe. Nor can we postulate it through logic because honestly we have NO knowledge of how or why gravity happens. It just does. In fact it's generally regarded as the least understood of the known fundamental forces of physics. While electricity and magnetism are inherently tied together as compliments, we have no such compliment to gravity. More puzzling, there is + and - electric fields but so far we've never seen a negative gravity effect. Is there a negative gravity effect? Antigravity? Well a lot of things familiar, exotic, and mind-bogglingly complicated have been through the physics labs of the last hundred years and it hasn't been seen in any degree, but this does not constitute proof that such a thing does not exist. Yet I'd like to add that it doesn't mean that creating such a fundamental force of nature with spinning tops and magnets is plausible either.

 

[dknguyen]

While we have observed the gravitational constant to be just that- a constant- and it has largely been proven to be true for celestial bodies, it's worthwhile to note that we haven't proven it's always true anywhere in the universe. Nor can we postulate it through logic because honestly we have NO knowledge of how or why gravity happens. It just does. In fact it's generally regarded as the least understood of the known fundamental forces of physics. While electricity and magnetism are inherently tied together as compliments, we have no such compliment to gravity. More puzzling, there is + and - electric fields but so far we've never seen a negative gravity effect. Is there a negative gravity effect? Antigravity? Well a lot of things familiar, exotic, and mind-bogglingly complicated have been through the physics labs of the last hundred years and it hasn't been seen in any degree, but this does not constitute proof that such a thing does not exist. Yet I'd like to add that it doesn't mean that creating such a fundamental force of nature with spinning tops and magnets is plausible either.

I'm still trying to wrap my head around how gravity can slow down light.

 

[Hero999]

I've always put that down to the mass energy equivalence.
https://en.wikipedia.org/wiki/Mass-energy_equivalence

But the most common explanation I've seen is that mass bends the space time. Perhaps I'm wrong, there again I might have an equally valid way of looking at things.

 

[audioguru]

The men on the moon in the sixties might have been a scam. The videos were so fuzzy that you couldn't see if it was real or just props.

The gravity is much less on the moon so you can jump higher which takes more time than if you jumped just a small amount. Maybe the scam was played in slow motion.

 

[Nigel Goodwin]

It's funny how it's always the Americans (and I include Canada in that!) that are doubtful about the moon landings? - I blame Fox Mulder for it!.

They convinced the Soviet Union, who would have loved to have exposed it, and who were in the best place to disprove it (having the required tchnology).

The technology back then was certainly capable of it, and probably more so than that for creating a hoax? - bear in mind Concorde dates from back then, and still hasn't been bettered!.

 

[dknguyen]

Free to think whatever you want is a double edged sword.

 

[j.p.bill]

Perhaps not for passengers, but the old SR-71 flies a bit higher & faster. It's a 1960s design.

 

[Nigel Goodwin]

Perhaps not for passengers, but the old SR-71 flies a bit higher & faster. It's a 1960s design.

Bit inconvenient though, only having space for one passenger, and having to wear those complicated flight and acceleration suits

I understand the in-flight meals aren't very good either?

 

[Oznog]

Space shuttle was designed and built in an era where 8-tracks were state-of-the-art.

Timex Sinclair "computer" would not hit the market until a yr after the maiden flight into space. Apple ][e? Another 10 yrs before it premiered!!

Just freaky how much they did without the power of modern computing and new materials/electronics. This was back when "miniature transistor radios" were quite a premium item but still beyond the means of many. Over the years the interior of the shuttle has been refitted with plenty of new computers, radios, and all sorts of equipment, but the shape, engines, and outer surface of the shuttle itself is basically unchanged.

 

[Nigel Goodwin]

Just freaky how much they did without the power of modern computing and new materials/electronics. This was back when "miniature transistor radios" were quite a premium item but still beyond the means of many. Over the years the interior of the shuttle has been refitted with plenty of new computers, radios, and all sorts of equipment, but the shape, engines, and outer surface of the shuttle itself is basically unchanged.

Which could explain the unfortunate disasters they have suffered?, the shuttle was never built as they wanted it to be, it was crippled by budgetary restrictions and was only a fraction of the use it should have been.

Is there any sign of a more usable launching system?, the shuttle has never really been a great success, with shuttle launches costing considerably more than the single use Soviet and French rockets.