Force and Space (Their Relation)

In summary, a black hole exerts a stronger force at its surface, since its radius is so much smaller. However, if a star comes over the horizon of a black hole's singularity then the star is sucked because of strong force exerted by the surface.
  • #1
Atran
93
1
Hi,

Let's say a 10 kg particle (X) whose volume is 1 m3, and another 10 kg particle (Y) whose volume is 1*10-24 m3.

Using the general force formula (F = GMm/r2), the same force is applied if I stand 1 meter before X or Y, but Y has smaller volume so it has to exert more force, right?

If so, how can I calculate that?
Thanks for help.
 
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  • #2
Atran said:
Using the general force formula (F = GMm/r2), the same force is applied if I stand 1 meter before X or Y, but Y has smaller volume so it has to exert more force, right?
No, why do you think that? (Note that that formula only applies strictly to point masses or for spherically symmetric mass distributions.)
 
  • #3
Doc Al said:
No, why do you think that? (Note that that formula only applies strictly to point masses or for spherically symmetric mass distributions.)

Because, from what I know, black holes exert much stronger force than the time they were stars. Stars becomes compressed to singularities to form black holes.
 
  • #4
Atran said:
Because, from what I know, black holes exert much stronger force than the time they were stars.
They exert a stronger force at their surface, since their radius is so much smaller. But replace an ordinary star with a black hole of the same mass and it will exert the same gravitational force on you as long as you stay the same distance from it.
 
  • #5
Doc Al said:
They exert a stronger force at their surface, since their radius is so much smaller. But replace an ordinary star with a black hole of the same mass and it will exert the same gravitational force on you as long as you stay the same distance from it.

I'm little confused, now if a star comes over the horizon of black hole's sigularity then the star is sucked because of strong force exerted by the surface? How comes a surface of particle playing role in exerting force?

In Newtonian physics using the force formula. Is (r) the distance between two centered points of particles? If so, what is the point of a mass? Since (r) never equals zero...
 
  • #6
Atran said:
I'm little confused, now if a star comes over the horizon of black hole's sigularity then the star is sucked because of strong force exerted by the surface? How comes a surface of particle playing role in exerting force?
I'm not sure I understand what you're asking. A black hole is tiny--thus you can get way too close, where the gravity is overwhelming. A black hole with a mass equal to our sun would have a Schwarzschild radius of about 3,000 m.

In Newtonian physics using the force formula. Is (r) the distance between two centered points of particles? If so, what is the point of a mass? Since (r) never equals zero...
Again, I'm not sure what you're asking. Think of the 'r' being the distance between two spherical bodies. Shrinking one of those bodies into a point won't change the distance between them.
 
  • #7
Doc Al said:
I'm not sure I understand what you're asking. A black hole is tiny--thus you can get way too close, where the gravity is overwhelming. A black hole with a mass equal to our sun would have a Schwarzschild radius of about 3,000 m.

I mean, how is the gravitational force very strong if you are within black hole's event horizon? Even if its mass is about our sun's mass.
 
  • #8
Doc Al said:
Again, I'm not sure what you're asking. Think of the 'r' being the distance between two spherical bodies. Shrinking one of those bodies into a point won't change the distance between them.

I mean, for example: Two charged spheres are attached/attracted to each other, is the distance between them 0 or the sum of their radius (sphere(1) radius + sphere(2) radius)?

I think that the distance never gets to zero, so the force approaches infinity as the distance approaches zero.
 
  • #9
Atran said:
I mean, for example: Two charged spheres are attached/attracted to each other, is the distance between them 0 or the sum of their radius (sphere(1) radius + sphere(2) radius)?
I don't know why you've introduced charge, but for two spherical masses the gravitational force will be calculated using the distance between their centers.
 
  • #10
Doc Al said:
I don't know why you've introduced charge, but for two spherical masses the gravitational force will be calculated using the distance between their centers.

I did that just for make it less arguable, because If it were gravitational force then someone might respond that the force between the two masses is too small, unless the masses were have been said to be huge enough.

My central problem is: If a black hole exerts the same force as a same-mass star, then how the black hole absorbs everything, even light?
 

1. What is the relationship between force and space?

The relationship between force and space is that force is a vector quantity that acts upon an object to change its motion or shape, while space is the three-dimensional extent in which all matter exists. In other words, force is the cause of change in an object's position or shape within space.

2. How does force affect the space around an object?

Force can affect the space around an object in various ways. For example, a force applied on an object can cause it to move in a certain direction, thus changing its position in space. Additionally, force can also cause changes in an object's shape or size, which in turn affects the space it occupies.

3. What is the role of space in determining the amount of force needed?

The amount of force needed to change an object's motion or shape depends on the amount of space it occupies. For instance, a larger object will require a greater amount of force to move or change its shape compared to a smaller object occupying less space. This is because larger objects have more mass and more resistance to changes in motion or shape.

4. How do force and space interact in the laws of physics?

Force and space are fundamental concepts in the laws of physics. The three laws of motion, formulated by Sir Isaac Newton, describe the relationship between force, mass, and acceleration in an object. The laws of gravity also involve the interaction between objects in space, where the force of gravity is dependent on the masses and distances between them.

5. Can force exist without space?

No, force cannot exist without space. Force is a physical quantity that requires an object to act upon in order to produce a change. This implies that force needs space to act upon an object and cause changes in its motion or shape. Without space, force would have no effect as there would be nothing for it to act upon.

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