Gravitational potential energy of asteroid

[Dadface]

OH. i see. but shouldn't the summation of forces be weight + mrw^2 = tension at the equator?

The weight acts vertically downwards and the tension acts vertically upwards.There is a resultant(centripetal) force which acts vertically downwards,in the same direction as the weight,which is equal to weight-T.It may be easier to see it if you sketch a free body force diagram and mark in the direction of the resultant force,

 

[quietrain]

oh. i forgot centripetal force is resultant. i was drawing the free body diagram including it as a force :X.

it kind of reminds me of the vertical swinging of a string attached to a mass.

thanks!

anyway, so if potential energy is defined to be 0 at infinity, is potential 0 at infinity too?

 

[Dadface]

oh. i forgot centripetal force is resultant. i was drawing the free body diagram including it as a force :X.

it kind of reminds me of the vertical swinging of a string attached to a mass.

thanks!

anyway, so if potential energy is defined to be 0 at infinity, is potential 0 at infinity too?

We can only calculate how potential energy changes with separation and the choice of an infinite separation and then the choice of calling the potential at infinity zero are both arbitary choices but nevertheless generally agreed to be the choices that are most useful and easiest to work with.Someone else may decide to choose a separation of two million and twelve point five metres and choose that the potential at such a separation is fifty three point zero seven J/kg.They might be able to calculate how the potential energy changes with separation but the calculations will be more messy and not easily followed by others.

 

[quietrain]

ic thanks

 

[mikeph]

This video was the final part of my dissertation last year, basically a minute long showing how you can have a satellite orbit around the sun in a very weird but stable path, half of the orbit it will move faster than the earth, then just before it reaches it, it slows down and the Earth almost catches up with it, like a funny cosmic cat and mouse.

The simulation is 2D but in a 3D analogue a similar thing happens. I think they've found an object that does this with Mars.edit- I didn't make it clear, the central circle is the sun, and the circle on the right is Jupiter, I think the mass ratio was about 10^3 in this simulation. It is of course in a rotating reference frame, basically using a multistep iterative method with a rotating coordinate transform added onto the end of it

 

[quietrain]

:X somehow that graffiti looked like marsian to me

thanks though