Is black hole just massive particle ?

[vlad777]

Depending on the speed of the projectile, you would have to fire it at an angle.
More speed, smaller angle.
And this way you loose most of the energy at an impact. Like shooting a target.
What trash said is landing on the target with no bang.

 

[MrAl]

Hi,

Well, he he, if you send a rocket into the sun you're going to get a bang

 

[vlad777]

Planets were also mentioned.
As for the Sun maybe the rocket would just melt?

 

[ericgibbs]

Planets were also mentioned.
As for the Sun maybe the rocket would just melt?

It would be safe enough if you went at night.!

 

[vlad777]

Ha ha, yes, that could be a good strategy

 

[trash]

But just because the Space Shuttle has to loose energy to land on Earth, that doesnt mean that everything has to loose energy before it can come down. With no atmosphere a rocket would not have to loose energy before it gets to that planet with no atmosphere. It could loose that energy when it hits the planet, so it would loose lots of energy alright but not until it hits.

But you've got the cart before the horse. In order for the spacecraft to hit the planet it requires a change in energy.
Netwons first law. An object that is in motion will not change its velocity unless an unbalanced force acts upon it.

You're somehow trying to say that a bullet cant hit a target unless it looses all it's energy FIRST.

This is the exact same thing, just you're thinking in absolute terms and not in relative terms.
The bullet needs energy to move. This is a STATIC model in newtonian physics. Your target is at relative rest with respect to the bullet.

What I'm saying is that you're holding the gun and you're moving at the speed a bullet would be travelling. NOW try and hit the target ! How much energy do you need to make the bullet hit the target ?

In space, the sun is moving, your rocket is moving. This is basic relativity. EVERYTHING in the universe is ALWAYS moving. They are never at rest (unless it is with respect to each other).

Remember that this is about material falling into black holes, matter has kinetic energy that it must lose in order to fall in.

Lets bring it back to a marble rolling down a funnel. You roll the ball around the rim of the funnel. This represents it's initial velocity.
Now the ball starts to roll and roll into or fall into the funnel. But it does this because it loses energy. If it did not lose kinetic energy then the ball would roll around the rim forever.
The ball falls down the funnel by losing energy as sound and heat through friction.

It's just a simple example of Netwon's first law.

Now replace the funnel with a black hole and the marble with something like an asteroid. How does the asteroid lose energy to fall in ?
There is no air, no friction, no sound .... How does it lose the kinetic energy of it's orbit ?


This isn't a trick question. It's a real world problem and one which highlights how the universe works.

 

[MrAl]

But you've got the cart before the horse. In order for the spacecraft to hit the planet it requires a change in energy.
Netwons first law. An object that is in motion will not change its velocity unless an unbalanced force acts upon it.


This is the exact same thing, just you're thinking in absolute terms and not in relative terms.
The bullet needs energy to move. This is a STATIC model in newtonian physics. Your target is at relative rest with respect to the bullet.

What I'm saying is that you're holding the gun and you're moving at the speed a bullet would be travelling. NOW try and hit the target ! How much energy do you need to make the bullet hit the target ?

In space, the sun is moving, your rocket is moving. This is basic relativity. EVERYTHING in the universe is ALWAYS moving. They are never at rest (unless it is with respect to each other).

Remember that this is about material falling into black holes, matter has kinetic energy that it must lose in order to fall in.

Lets bring it back to a marble rolling down a funnel. You roll the ball around the rim of the funnel. This represents it's initial velocity.
Now the ball starts to roll and roll into or fall into the funnel. But it does this because it loses energy. If it did not lose kinetic energy then the ball would roll around the rim forever.
The ball falls down the funnel by losing energy as sound and heat through friction.

It's just a simple example of Netwon's first law.

Now replace the funnel with a black hole and the marble with something like an asteroid. How does the asteroid lose energy to fall in ?
There is no air, no friction, no sound .... How does it lose the kinetic energy of it's orbit ?


This isn't a trick question. It's a real world problem and one which highlights how the universe works.

Hello,


Im afraid you are talking about one thing and i am talking about another thing, so we're not both on the same page so to speak. This happens from time to time in forums so i'll end my replies to these issues.

 

[trash]

No problems. I prefer to clarify differences and misunderstanding. Whether they are mine or somebody else's, I've always got the time.

For those still confused I thought of another example.
Does the water always go down your sink in a straight line or does it spiral down ?

Or - How fast is the moon falling towards the earth ?

When things fall they lose energy in the process. (consider this with the moon)
Either atmospheric drag or friction and sound and heat.

It's a very simple question. If a body is orbiting a black hole. How does it fall in ?

I can give an example of a charged particle like a proton. As it falls in it emits bremsstrahlung (braking radiation) in the form of X-rays.
But this happens at high velocities on an atomic scale very close to the event horizon.

On a macro scale a pair of stars can have a gravitational interaction. Placing one in an elliptical orbit around the black hole and ejecting the other from the galaxy in the process.

But what happens to a body in a circular orbit around a black hole. Does it's orbit decay through the emission of gravity waves or some other process ?
Does it's orbit even decay ?

 

[ericgibbs]

Or - How fast is the moon falling towards the earth ?

The Moon is not falling towards the Earth, its in fact moving away at approx 2cms/year

 

[vlad777]

trash,

I get what you are saying, but it is not always like that.

In my post #7 in this thread you can see a comet hit the Sun, not fall on the Sun.

Comet would slightly miss the Sun but the gravity of the Sun changed it's trajectory,
and the comet hit the Sun WITH ALL IT'S KINETIC ENERGY.

 

[trash]

Oh yes, of course.
But what we're seeing with the comet is actually the same thing. The difference is that the comet already has a low enough orbital velocity with respect to the sun to ensure that it will collide with the sun.

If the comet is an extra solar object then it never had any orbital velocity. So it was on a collision course without the effect of gravity. When the comet collides with the sun, conservation of energy is still there. The energy of the sun and the comet are added together.

Lets consider what happens if the comet is not an extra-solar comet. It comes from the Ort cloud. These objects are in a high orbit around the sun. It is a collision or a gravitational slingshot that causes one of these objects to lose orbital velocity and fall towards the sun. Conservation of energy happens here too. In the case of the slingshot some equal momentum/mass was displaced. So another Ort object was either ejected from the solar system, placed in a higher orbit or it's momentum cancels with something like a collision.

Conservation of momentum and conservation of energy is what it is all about.

The Moon is not falling towards the Earth, its in fact moving away at approx 2cms/year

Shhh ! It was a trick question.

But since the cat is out of the bag, the question now becomes. The moon is falling up ! This means that it's gaining energy.
More conservation of energy.

Where does it get this energy from ?


Back to objects falling; We can see that objects in orbit need to lose energy in order to fall by giving it to something else.
Objects which are not in orbit will fall straight in provided that both objects have a relative zero velocity with each other.

 

[carrotSnack]

But since the cat is out of the bag, the question now becomes. The moon is falling up ! This means that it's gaining energy.
More conservation of energy.

Where does it get this energy from ?

The Earth's rotational energy.
Do I get a prize?

 

[MrAl]

Hello,


The Moon is falling toward the Earth, it's just that it falls less over time so the distance between the Earth and Moon is getting bigger over larger periods of time. The Moon doesnt hit the Earth because it's outward motion cancels the inward motion and that keep it orbiting. The outward motion comes from the Moon always trying to keep on a straight path, while the inward motion comes from the forces of gravity.

If you could stop the Moon from rotating around the Earth it would be pulled into the Earth. If you could make it rotate faster, it would move away from the Earth in a spiral pattern.

[Side fact] One side of the Moon always faces the Earth because of the slight difference in mass on one side.

 

[trash]

@ MrAl

"The Moon is falling toward the Earth, it's just that it falls less over time"
But doesn't everything fall at the same rate ? How can something fall 'less' ?

" If you could make it rotate faster, it would move away from the Earth in a spiral pattern."
This IS what the moon is doing. So it's rotating faster. Where is this orbital energy coming from ?

 

[MrAl]

@ MrAl

"The Moon is falling toward the Earth, it's just that it falls less over time"
But doesn't everything fall at the same rate ? How can something fall 'less' ?

" If you could make it rotate faster, it would move away from the Earth in a spiral pattern."
This IS what the moon is doing. So it's rotating faster. Where is this orbital energy coming from ?

Hi,

Do a diagram, figure it out

 

[trash]

There's no need for a diagram, there's a simple answer.
I'm not trying to embarrass you, just trying to clear up a misunderstanding and show the relationship to large orbiting objects falling.

Don't make me give Carrotsnack another prize
I know he's got his tidal charts ready for an answer.

 

[MrAl]

Hello,


Dont worry, you cant embarrass me.

I didnt want to get in to a long winded 'discussion' about any of this stuff, just present some facts. But you insist on trying to apply high school physics to real world problems and that presents some difficulties. For example, your last question was how does something fall 'less'. Well if you view it over time and it falls at 5 feet per second and later some time say 1 minute later it falls as 4 feet per second, now it's falling less.
The word 'less' means that some quantity has decreased. That's why i said do a diagram. You'd see the distance become greater over the same time period. But since we used the word 'fall' and the distance was increasing, that means it's falling 'less'
.
We have to use a relational operator because it is falling but there's a change in the fall path. It's not that it goes from falling to not falling or vice versa, it's just a change in the way it does the same thing. We usually just say "it is moving away from the Earth" because we dont usually try to account for the full rotational motion. But when we try to map out it's motion we need to understand some laws of gravity and things like how orbits work.

So do a diagram, look at the distance from the Moon to the Earth and see what it does, then describe it.

 

[trash]

I think you're missing the point of this entire thread then. Because it is about the properties of black holes.

A diagram ... why ? Ok.. since your incapable of answering the question I'll give you the answer.

The word 'less' means that some quantity has decreased. That's why i said do a diagram. You'd see the distance become greater over the same time period. But since we used the word 'fall' and the distance was increasing, that means it's falling 'less'

That wins my award for the worse attempt at back pedalling I've ever seen. You have a promising careerer in Australian politics if you ever immigrate.

The Moon's orbit is increasing because it is gaining energy.
It gets this energy from the earth's rotation and tidal effects with the moon.

This means the earth's rotation is slowing and the energy transferred to the moons orbital velocity.

As the Earth rotates there is a small gravitational tug between the moon and the earth.

No double negatives, no diagrams. Just a simple explanation of a gravitational interaction.

Which brings as back to the objects in orbit falling.
How do they lose energy. It's a simple question which needs nothing but a simple answer.
In examples of satellites in low earth orbit, atmospheric friction de-orbits satellites.
But a large single object like an asteroid cannot do this. A black hole doesn't have an atmosphere, so atmospheric drag can't bring it down.
What can cause it to de-orbit ?

In the case of the earth-moon interaction, the earth's uneven shape influences the moon.
These are simple newtonian answers to common observations.

But black holes are aren't so easily observed so we need to run models in order to better explain them.
In the case of a black hole, it would be safe to assume that the surface (or event horizon) is smooth or a black hole down not have any gravitational anomalies to cause a similar effect in large bodies orbiting them.
I've already explained why microscopic particles in orbit close to the event horizon can fall in. They lose their energy by emitting bremsstrahlung in the form of X-rays. Black holes are observed emitting X-rays.

I've also explained how binary objects can gravitationally sling shot each other so that one object is ejected while the other falls.
https://en.wikipedia.org/wiki/Stellar_kinematics#Production_methods

In the case of very massive objects like a neutron star or another black hole, the theory is that they emit gravitational waves. https://en.wikipedia.org/wiki/Gravitational_wave#Power_radiated_by_orbiting_bodies
This is a reasonable enough theory. We haven't yet detected gravity waves so if they don't exist then there is a problem with our model of gravity.
If they do exist, then we should be able to use them to make other accurate measurements or the universe.


It's not a trick question. It's a simple question. How do macro objects lose orbital energy and fall into a black hole ?

 

[MrAl]

I think you're missing the point of this entire thread then. Because it is about the properties of black holes.

A diagram ... why ? Ok.. since your incapable of answering the question I'll give you the answer.


That wins my award for the worse attempt at back pedalling I've ever seen. You have a promising careerer in Australian politics if you ever immigrate.

The Moon's orbit is increasing because it is gaining energy.
It gets this energy from the earth's rotation and tidal effects with the moon.

This means the earth's rotation is slowing and the energy transferred to the moons orbital velocity.

As the Earth rotates there is a small gravitational tug between the moon and the earth.

No double negatives, no diagrams. Just a simple explanation of a gravitational interaction.

Which brings as back to the objects in orbit falling.
How do they lose energy. It's a simple question which needs nothing but a simple answer.
In examples of satellites in low earth orbit, atmospheric friction de-orbits satellites.
But a large single object like an asteroid cannot do this. A black hole doesn't have an atmosphere, so atmospheric drag can't bring it down.
What can cause it to de-orbit ?

In the case of the earth-moon interaction, the earth's uneven shape influences the moon.
These are simple newtonian answers to common observations.

But black holes are aren't so easily observed so we need to run models in order to better explain them.
In the case of a black hole, it would be safe to assume that the surface (or event horizon) is smooth or a black hole down not have any gravitational anomalies to cause a similar effect in large bodies orbiting them.
I've already explained why microscopic particles in orbit close to the event horizon can fall in. They lose their energy by emitting bremsstrahlung in the form of X-rays. Black holes are observed emitting X-rays.

I've also explained how binary objects can gravitationally sling shot each other so that one object is ejected while the other falls.
https://en.wikipedia.org/wiki/Stellar_kinematics#Production_methods

In the case of very massive objects like a neutron star or another black hole, the theory is that they emit gravitational waves. https://en.wikipedia.org/wiki/Gravitational_wave#Power_radiated_by_orbiting_bodies
This is a reasonable enough theory. We haven't yet detected gravity waves so if they don't exist then there is a problem with our model of gravity.
If they do exist, then we should be able to use them to make other accurate measurements or the universe.


It's not a trick question. It's a simple question. How do macro objects lose orbital energy and fall into a black hole ?

Hello,

You like to ask a lot of questions and then wont accept anyone else's answer about anything, and that is why i refused to answer and also refused to comment on several of your points in the past. You're making all the points, you're insisting on what the most important points are, you're also now insisting on what framework they should be answered within, and for lack of information you want to go on an assumption binge, you're doing all the driving, so you answer all the questions and dont bother me with any of it.

 

[april]

Yep he's been like that from the start - another been there knowitall. Talks as if he has been to the moon and to a black hole
Ho Hum !