/sci/ - Science & Math

>>1809754
>That means that their gravitational energy increases.

Nope, that is totally wrong.
It decreases there gravitational energy

As the distance between two celestial bodies increases, the gravitational force decreases, right?

>>1809760
Explain, please? I hate to admit I've never really had a strong grasp of the expansion of the universe.

the gravitational energy of a body isn't the same thing as the gravitational force acting on it.

i'm still right.

try again.

>The expansion of the universe increases the distance between planetary bodies. That means that their gravitational energy increases.
Heat death averted.
GoodJobTeam.jpg.avi

But seriously, that is pretty nifty, never thought of it that way before.

>>1809765
Yes, but the potential energy (re: kinetic energy if the objects are then brought close) increases.

>>1809765

But I will say that I like the way you think OP.

>>1809754 That means that their gravitational energy increases.

No it means the gravitational force(not energy) decreases.

The rest of what you wrote isn't worth responding to because it is based on flawed assumptions.

>>1809779
Force is not energy, stop correcting one for the other, then saying he's wrong because he said increase instead of decrease.

It's like me saying x>5 then you telling me 'no, you meant y, and y<4'. That's different altogether.

>>1809770
>>1809767
>Yes, but the potential energy increases.

Are you fucking retarded or just a troll?
Do you study engineering? YOu sound like a fucking faggot!

The potential energy (PE) of gravity is inversely proportional to distance. The closer things are, the more PE, the farther things are, the less PE.

FUCK OFF!

>>1809779

So the gravitational energy doesn't increase, ey? Try explaining where the kinectic energy a stone gains after lifting it from the ground and dropping it comes from then.

>>1809779
But the potential energy of two bodies as a result of their gravity is proportional to the distance between them. OP is basically describing dark energy/the cosmological constant/whatever.

>>1809754

FU OP!

Now I want a double bacon burger... :P''

>>1809785
Hey moran, there's a negative sign. U=-GMm/r. As things come closer, the potential energy decreases.

ill just consider this a proof of god and be done with it

>The expansion of the universe increases the distance between planetary bodies. That means that their gravitational energy increases.
>increases the distance between planetary bodies. That means that their gravitational energy increases.
>increases the distance = gravitational energy increases

Are you FUCKING RETARDED ?

>>1809825
It is true. U=-GMm/r. At infinity the potential energy is 0. At any finite distance, the energy is negative and finite.

Start an object at rest 1 AU from the Sun. When it hits the Sun, it will have some kinetic energy. Set an object at rest 2 AU from the Sun. When it hits the Sun it will have greater kinetic energy. Where did the extra energy come from? The extra gravitational potential energy.

>>1809754
My question, why the fuck is this energy trying to fuck us over? ='(

>gravitational energy is the gravitational force multiplied by the distance through which the body moved.

As is seen in the picture the force decreases by square of the distance and when you multiply it by the distance(in this case [r]) the overall energy is decreased by the distance, when the objects retain the same mass. Or maybe I'm just mistake, due to the fact I'm just a simple doctor of medicine.

A thought experiment for those who declare OP wrong:
There is a universe containing two objects only, each with some mass. At t=0, they are arbitrarily close to each other, and have U (potential energy)=0. As the universe expands to some time, say t=1, the objects are now separated by some distance. If we we to allow the objects to collide, there is some obvious kinetic energy there. At a later t=2, the objects are even further apart. Should they be allowed to fall together, there's an even greater energy there.
You've obviously memorized your precious formulas wrong, it seems that things further away have *greater* energy due to gravity.

When an object is 5,000 feet in the air it has more potential energy than when it at 5 feet, because it has 4,500 more feet to fall. It is also true that the gravitational force exerted on it is weaker at 5,000 feet than at 5 feet. I believe this is what OP is trying to say.

>>1809862
>just a simple doctor of medicine.
i am sorry

>>1809871
yes, that's right.

>>1809785

>>1809901
lol

Residual energy from the big bang?

>>1809785
>The potential energy (PE) of gravity is inversely proportional to distance.

That's not really true, OP. Gravitational potential energy increases as <span class="math">\frac {-Gm_1 m_2} r[/spoiler]. In your example r goes to infinity, but the potential never increases above 0, which means that the gravitational energy increase isn't really infinite.

OP here

>>1809940
Indeed.

And also, I guess you could assume that the expansion would go unhindered when the expansion rate gets big enough as gravity wouldn't catch up, so to speak. And therefore no energy would be required in the expansion. (Big Rip?)