The Scientific Curiosity Thread!

[Known_Unknown]

This thread is for any questions you may have regarding science! Everything you ever wanted to know from Quantum Theory to Evolution is welcome!

Post your questions and those of us knowledgeable in those subjects will try to answer.

To begin, here's a question that's I've been wondering about: Why don't the planets just spiral into the sun? If there's a gravitational force acting on them, shouldn't all of them just fall into the Sun instead of perpetually going around it?

 

[pmaitra]

Someone please explain why the multi-link suspension (automobile) is claimed to be superior.

No beating around the bush please. Don't tell me Audi does it, BMW does it, blah blah blah. I already know all that. Explain to me how it works, and why it is claimed to be better than most other suspensions; or whether it is a fake marketing claim.

Thanks.

N.B.:
Caution, I have already read the entire site below, so no bovine droppings please.
http://www.carbibles.com/suspension_bible.html

 

[Razor]

This thread is for any questions you may have regarding science! Everything you ever wanted to know from Quantum Theory to Evolution is welcome!

Post your questions and those of us knowledgeable in those subjects will try to answer.

To begin, here's a question that's I've been wondering about: Why don't the planets just spiral into the sun? If there's a gravitational force acting on them, shouldn't all of them just fall into the Sun instead of perpetually going around it?

If I remember right, it's centrifugal force.

Consider a ball attached to a string being whirled around by your hand. At a particular point of time, if I were to cut the string with my katana, the ball would fly away, taking a tangential path. The reason why the ball moves away in a tangential path is because, of inertia. The direction of the ball is being changed at every instant by the force applied by your hand (via string). So I believe, the centrifugal force is basically the inertia that tries to keep the ball moving in the direction it was moving in, at the previous instant.

With respect to the planets, I suppose the gravitational pull of the Sun tries to pull the planets (and other bodies) toward itself, in a spiral path (which creates a centrifugal force), and supposedly these forces balance each other out, giving us a near elliptical orbit.

Edit: I think, this is a great idea. I propose this be made a 'Sticky'.
Scientific awareness and quenching of curiosity is always a good thing.

 

[pmaitra]

Centrifugal Force = -Gravitational Force

Therefore, equilibrium.

Correct me if I am wrong.
@Known_Unknown, @Razor

Edit: http://en.wikipedia.org/wiki/Centripetal_force (equations)

 

[Razor]

Centrifugal Force = -Gravitational Force

Therefore, equilibrium.

Correct me if I am wrong.
@Known_Unknown, @Razor

Edit: Centripetal force - Wikipedia, the free encyclopedia (equations)

Thanks. You are correct.
So a centripetal force creates a reactionary force called centrifugal force. And in the case on planetary arrangements, centripetal force is the gravitational force.
And they balance each other. Beautiful.

 

[Known_Unknown]

If I remember right, it's centrifugal force.

Consider a ball attached to a string being whirled around by your hand. At a particular point of time, if I were to cut the string with my katana, the ball would fly away, taking a tangential path. The reason why the ball moves away in a tangential path is because, of inertia. The direction of the ball is being changed at every instant by the force applied by your hand (via string). So I believe, the centrifugal force is basically the inertia that tries to keep the ball moving in the direction it was moving in, at the previous instant.

With respect to the planets, I suppose the gravitational pull of the Sun tries to pull the planets (and other bodies) toward itself, in a spiral path (which creates a centrifugal force), and supposedly these forces balance each other out, giving us a near elliptical orbit.

Edit: I think, this is a great idea. I propose this be made a 'Sticky'.
Scientific awareness and quenching of curiosity is always a good thing.

I've heard a similar explanation before, that the Sun pulls the planets toward itself, but this is countered by the planets' tendency to move away in a straight path. So when a planet is in motion, according to Newton's (1st/2nd/3rd?) law of motion, unless an external force acts on it, it will maintain its inertia i.e. motion if it is moving, or rest as the case may be.

So follow up question: What set the planets in motion in the first place? If they were to be stationary, would they be pulled in straight into the Sun? How about an astronaut in space, outside the Earth's orbit? Is he "falling" into the Sun or revolving around it?

 

[pmaitra]

Thanks. You are correct.
So a centripetal force creates a reactionary force called centrifugal force. And in the case on planetary arrangements, centripetal force is the gravitational force.
And they balance each other. Beautiful.

Yes, but there is a caveat. Many celestial orbits are not exactly circular. I could look it up, but please explain in precis if you could?

 

[Razor]

I've heard a similar explanation before, that the Sun pulls the planets toward itself, but this is countered by the planets' tendency to move away in a straight path. So when a planet is in motion, according to Newton's (1st/2nd/3rd?) law of motion, unless an external force acts on it, it will maintain its inertia i.e. motion if it is moving, or rest as the case may be.

So follow up question: What set the planets in motion in the first place? If they were to be stationary, would they be pulled in straight into the Sun? How about an astronaut in space, outside the Earth's orbit? Is he "falling" into the Sun or revolving around it?

I don't know what started it all.
Stationary wrt what frame. If it's with respect to the Sun, it is not possible. You can't be stationary wrt the Sun (in our Solar System). The astronaut I believe will revolve. I think the inertia on the astronaut will make him wanna travel in a straight line, but the pull of the Sun will try to suck him straight in. Maybe the circular(or elliptical, to be precise) path is a vector sum of both these velocities.

PS: Not an expert by any measure, so you'll find a lot of 'maybe', 'suppose' etc. I'm just throwing out ideas, so that people can refute.

 

[Razor]

Yes, but there is a caveat. Many celestial orbits are not exactly circular. I could look it up, but please explain in precis if you could?

Wow. I don't really remember, but there are a set of three laws( was it Kepler?). I'll get back to you after reading that.

 

[blank_quest]

I've heard a similar explanation before, that the Sun pulls the planets toward itself, but this is countered by the planets' tendency to move away in a straight path. So when a planet is in motion, according to Newton's (1st/2nd/3rd?) law of motion, unless an external force acts on it, it will maintain its inertia i.e. motion if it is moving, or rest as the case may be.

So follow up question: What set the planets in motion in the first place? If they were to be stationary, would they be pulled in straight into the Sun? How about an astronaut in space, outside the Earth's orbit? Is he "falling" into the Sun or revolving around it?

What kind of "Motion" or the Motion in what kind of Manifold??

 

[Known_Unknown]

[/B]
I don't know what started it all.
Stationary wrt what frame. If it's with respect to the Sun, it is not possible. You can't be stationary wrt the Sun. The astronaut I believe will revolve. I think the inertia on the astronaut will make him wanna travel in a straight line, but the pull of the Sun will try to suck him straight in. Maybe the circular(or elliptical, to be precise) path is a vector sum of both these velocities.

Why so? Why can't you be stationary w.r.t the Sun?

Inertia is only a state, so if the astronaut's inertial state is motion in a straight line he should stay in a straight line and if he's at rest, he should stay at rest. It becomes more complicated since we haven't defined what direction yet, this could be away from the Sun on the plane of the solar system, directly towards the Sun again on the same plane, or perpendicular upwards or downwards to the plane, as gravity will probably cause a different net effect (vector addition) on motion in each of these directions.

 

[Cliff@sea]

So follow up question: What set the planets in motion in the first place? If they were to be stationary, would they be pulled in straight into the Sun? How about an astronaut in space, outside the Earth's orbit? Is he "falling" into the Sun or revolving around it?

The same force that created them i.e separated them from the larger mass of greater Sun that existed before the earth was formed ,

When u say stationary i believe u mean that if no other force is acting on them ,
and they themselves have no moving inertia ,

Yes If that were the case, they would collide into the sun .

 

[Known_Unknown]

What kind of "Motion" or the Motion in what kind of Manifold??

Manifold?

Well, what I got from the above posts was that gravity acts as a centripetal force, exerting an outward balancing (centrifugal) force which keeps the planets in motion. But this is actually not true because these forces balance each other exactly only in case of a perfectly circular orbit. But the planets don't follow circular orbits, they follow elliptical orbits, so the explanation above does not apply.

The other explanation I've heard that the planets originally must have been in some kind of straight line motion away from the Sun. This motion, combined with the inward pull of gravity (vector addition of the forces) keeps the planets in orbit.

 

[Known_Unknown]

The same force that created them i.e separated them from the larger mass of greater Sun that existed before the earth was formed ,

When u say stationary i believe u mean that if no other force is acting on them ,
and they themselves have no moving inertia ,

Yes If that were the case, they would collide into the sun .

Ahh, so coming back to our unfortunate astronaut, if he ends up outside the gravitational pull of the earth, then he will be slowly "falling" into the Sun? Not revolving around it, right?

 

[blank_quest]

Manifold?

Well, what I got from the above posts was that gravity acts as a centripetal force, exerting an outward balancing (centrifugal) force which keeps the planets in motion. But this is actually not true because these forces balance each other exactly only in case of a perfectly circular orbit. But the planets don't follow circular orbits, they follow elliptical orbits, so the explanation above does not apply.

The other explanation I've heard that the planets originally must have been in some kind of straight line motion away from the Sun. This motion, combined with the inward pull of gravity (vector addition of the forces) keeps the planets in orbit.

By manifold I mean dimension. And there is the Particle exchange between Sun and Planets for What I know keeps the planet into the constant influence of Field of Sun.No forces are possible without actual material exchange between two bodies and this is the base of field concept. forces are the result of "rate of material exchange" and "Polarity or spin" of these "Particle" and how they behave in combination . This may be catalyzed by Manifold in which the Body is present..

 

[Razor]

Manifold?

Well, what I got from the above posts was that gravity acts as a centripetal force, exerting an outward balancing (centrifugal) force which keeps the planets in motion. But this is actually not true because these forces balance each other exactly only in case of a perfectly circular orbit. But the planets don't follow circular orbits, they follow elliptical orbits, so the explanation above does not apply.

The other explanation I've heard that the planets originally must have been in some kind of straight line motion away from the Sun. This motion, combined with the inward pull of gravity (vector addition of the forces) keeps the planets in orbit.

Circles are a kind of ellipse with a single center rather than two.
I think it is easier to maintain an elliptical orbit rather than a circular orbit. (A single imbalance, like a meteor strike and the circular orbit might tend to become an elliptical one.)
If I find a better answer, I'll post it.

 

[Razor]

Ahh, so coming back to our unfortunate astronaut, if he ends up outside the gravitational pull of the earth, then he will be slowly "falling" into the Sun? Not revolving around it, right?

Nope he'll revolve because he is not free from other forces no matter how far he is from other bodies. So he'll slowly revolve in a spiral towards the Sun.
Also, suppose he did get very far away from the Earth's gravitational field. How did he do that? He must have an escape velocity. So he is in motion initially, which means he is not at rest, which means he won't go straight into the Sun.

 

[Known_Unknown]

By manifold I mean dimension. And there is the Particle exchange between Sun and Planets for What I know keeps the planet into the constant influence of Field of Sun.No forces are possible without actual material exchange between two bodies and this is the base of field concept. forces are the result of "rate of material exchange" and "Polarity or spin" of these "Particle" and how they behave in combination . This may be catalyzed by Manifold in which the Body is present..

Wow. This is totally new to me. Is there a name for this theory? It seems to be completely counter-intuitive, because if particle exchange was the basis of the orbital motion of planets, those particles would probably need to be exchanged at close to the speed of light. What particles are these?

Does this particle exchange apply to all forces? How about electromagnetic force?

 

[jalsa]

Someone please explain why the multi-link suspension (automobile) is claimed to be superior.

No beating around the bush please. Don't tell me Audi does it, BMW does it, blah blah blah. I already know all that. Explain to me how it works, and why it is claimed to be better than most other suspensions; or whether it is a fake marketing claim.

Thanks.

N.B.:
Caution, I have already read the entire site below, so no bovine droppings please.
Car Bibles : The Car Suspension Bible page 1 of 5

Multi-link suspension is the best bet if you want to balance between handling and ride quality. It is the best independent suspension, the tire can maintain contact with road under extreme cornering loads and also during trail-breaking into the corners.

Sudden undulations in the mid corner will unsettle a car with torsion-beam or double-wishbone suspension, a car equipped with multi-link suspension will hold the line better. Ride quality improves as you go faster with multi-link suspension.

Fiat Punto is an exception for this, even though it has torsion-beam suspension at the rear it handles as good as any premium sedan.

 

[blank_quest]

Wow. This is totally new to me. Is there a name for this theory? It seems to be completely counter-intuitive, because if particle exchange was the basis of the orbital motion of planets, those particles would probably need to be exchanged at close to the speed of light. What particles are these?

Does this particle exchange apply to all forces? How about electromagnetic force?

Search for "Gravitons" and you will come to know it from numerous resources on the net. en.wikipedia.org/wiki/Graviton There is a possible explanation that material and energy are exchangeable so when Bodies are under energy or "field influence" they will invariably be associated with some kind of Particle. Remember E=Mc2