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7

Actually, the process you described is not irreversible. What has happened is that potential energy has been converted to kinetic energy. It is possible to reverse the process by using a roller coaster kind of arrangement where the ball is redirected to go up a hill. In the end, its kinetic energy is converted back into potential energy. There is no ...


3

You need to keep the direction in mind. While the direction never makes the gravity negative, adding opposite directions will cancel out. I don't know if you are familiar with vectors? The length of a vector is always positive (strength of gravity) but it also has a direction (direction of gravity). If you add two vectors of equal length ("strength") but ...


2

Whenever you have a spherical shell with homogeneous mass, any object outside of it will feel a radial attraction, while any object inside will feel no gravitational force at all, since all the vectors cancel out. So, try to picture Earth as a collection of shells with distinct radii and density. If the particle is positioned inside some shells, but outside ...


2

Why do stellar boundaries exist? Stars do not have a hard boundary or surface in the sense that your question seems to suggest you are thinking. The sun looks like a nice, discrete sphere due to optical effects. What we call the surface of the sun is the photosphere. We call this the surface, because it is what we effectively see when we look at the ...


1

If this particle was travelling towards earth, where would its rest state be? If the particle is moving fast enough, the answer is nowhere. The particle will gain speed as it approaches the center of the Earth. The speed will be rather high at the point of closest approach to the center. The particle will lose speed as it moves away from the center of ...


1

Gravity is always additive. You can never add mass and reduce the gravitational force created. What does happen is that gravitational forces in opposite directions can cancel one another out, leaving 0 net force. If gravity wasn't always additive, it would mean that it would be possible for gravity to push things, instead of always pulling. This is not the ...


1

I would have to see the source to answer completely but my first guess would be that the relativistic jets from the black holes are pushing against each other. This might cause some strange wobbling but I would think eventually the equators would lineup and they would begin to orbit each other.



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