Is Gravity Elastic?

[sandyRoe]

When an object with an elliptical orbit is at its nearest to the Sun it must be experiencing a certain force of gravity. As it moves away from the Sun it must reach a point when the gravity that once held it is no longer strong enough to keep it in a circular orbit.
I know next to nothing about science, as this question probably shows.

[Noth43]

"I believe the ABers who know the answer think it's too difficult to explain to a layman. "

As a layman I don't know the answer, as a scientist I'm equally baffled.

[seadogg]

All I know is when I came off a climb on the Dente Blanche I didn't bounce when my backside met the glacier beneath. A long way beneath!

[shoota]

Surely for it to be in an elliptical orbit the object can never reach the point where its momentum overcomes the pull of the gravity otherwise it wouldn't be in the orbit? It would just wander straight on until it met something else or became subject to another field of gravity.
I can see that its speed may decrease as it moved away until it dropped to a point where the weakened gravitational pull was sufficient to pull it back, causing it to accelerate as it neared the sun and 'slingshotting' it out the other side.
Whether spin was imparted to the object or not would depend on the shape of the object (?)

[Tilly2]

I'll get my coat!

[Psybbo]

I'm with you, Tilly

[Tilly2]

Come on then. Where shall we go?

[Psybbo]

The nearest pub

[Tilly2]

There's one round the corner called 'Down to Earth'. We'll go there.

(Off to watch Stella)

[modeller]

The reason for the elliptical path is because the force of gravity is not even
on the earth or on the sun and therefore the path is not even.
These forces are also uneven because of the tilt of the earth at any particular moment in time.
In addition there are other sources of gravity eg. our own moon and planets affects the path .

[mrs_overall]

I don't think gravity can be elastic as gravity will not hold my knickers up

[shoota]

Will anything?

[mrs_overall]

On the rare occasion I wear them...

[shoota]

Mrs(command)O

[mrs_overall]

lol @ shoota

[vascop]

Modeller: The ellipticity of the orbits have nothing to do with gravity being uneven.
If you do the maths for a body moving around another body with an inverse square law of attraction between them, then the orbit turns out to be elliptic with the sun at one of the foci.
Of course in reality there are more than two bodies involved and these do have an effect on the orbit, but even f they weren't present the orbit would still be elliptical.

[DangerUXD]

no

[mibn2cweus]

DangerUXD
no
20:56 Sun 10th Feb 2013

. . . but space is.

[jake-the-peg]

Gravity obeys an inverse square law - this was Newton's great discovery

Although this sounds complex it's not really

When the distance gets greater the force gets less by the sqaure of that - an example

when it's twice as far away the force is 1/4 ( 4 being the square of 2)
when it's 3 times as far away the force is 1/9 etc

Now what this means in principle is several types of trajectory are possible - some are nearly circular (like the planets), some highly eliptical (like regular comets) and others are open like comets that do not return.

These open trajectories are usually hyperbolic.

The shape of orbit depends largely on the speed of the body and the angle it comes in at.

The body moves faster as it gets closer to the sungiving it more energy to escape again before slowing down and being dragged back

http://upload.wikimedia.org/wikipedia/en/thumb/6/69/Kepler-second-law.gif/220px-Kepler-second-law.gif

Gravity is constant (but tails off with distance) - I'm not sure elastic is quite the same - Imagine a hill that gets steeper the closer you get to the summit



Kepler first discovered all about this and formulated 3 laws about it

http://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion