hey thanks guys, I've been away for a while.
im pretty sure I am understanding it all now, so thanks heaps for all your help. ill see if i can give my teacher like a draft, to make sure what I've done is what he wanted, and if it isn't ill try to figure it out, but if i can't expect to see me...
with T^2 proportional to r^3, how do you put values in?
is it
(T^2) = (r^3)
or
(T^2) / (r^3) = same for all planets?
because when you sub in values for Earth with the first one, it doesn't equate.
T = 31 493 080s
r = 149 600 000 000m
already you can see T^2 won't = r^3
am i...
i underdstand you putting ALOT of effort into explaining this to me, but i still don't really get it.
Why can't you compare a planets period in seconds to its radius is metres and come up with a T^2 r^3 ratio? like it doesn't work.
why do we try to prove keplers third law? how will that...
so how would that help prove the inverse square law?
is T^2 (propotional to) r^3 related to F (proportional to) 1/r^2 ? sorry for all the questions I am just really not catching on...
also, for T^2 (propotional to) r^3, is r the same value used for the radius of a planets orbit? i noticed...
on a bit on an unrelated topic, how do you post those equations and terms and stuff in the larger black text?
but back on topic, is the above asumption, sut = used, sorry for the bad spelling. anyway anyone still avaiable to help me out?
so that's using T= 2(pi)r/v right?
and is that sut to show r and v are correct?
and does anyone else have any other ideas about doing the queisotn with the 'hence' sort of approach?
thanks HEAPS to older dan for that little proof, that makes complete sense! i think the only problem is the question is set out like "find this and this and this and hence prove the inverse square law"
im pretty sure the teacher wants me to work out some forces, and then compare them to other...
i don't follow.
"Equate that to the gravitational force, and the mass of the planet divides out."
what does this mean? if my calculations are right, then why don't my forces match up with the inverse square law? is there a step I am missing or something?
thats what i did, but when i compare radiuss the forcves don't match up. My reasoning is if r EARTH = 10000000 (obviosuly not right) and r MARS = 20000000, then ratio is 1:2, and the force of Mars will be 1/4 ( 1/(2r)^2 )the force of earth, providing F proportional to 1/r^2 is correct
i also used the above equation and the forces work out extemelly similar to the F=ma equaiotn (only different subject to rounding).
and yes that is the the equation it refers to, as in if the radius doubles, the force will quarter.
since I am not considering the masses however, can't it just...
im only a year 12 but wouldn't there be more friction simply because there's more surface contact? and the polish just creates a rougher bumpy surface maybe?
alright, these are done by hand so it might look a little messy:
start with mercury
r = 57900000000m } found on internet
m = 3.3 x 10^23
now since v = (square root) Gm/r [sub in values... m = mass of sun]
v= 47927.7m/s
since a = v^2/r = [sub in values]
a = 0.04m/s^2...
hey guys,
im doing an investigation into the accuracy of the "inverse square law" (any two particles with experience a mutually attractive force yadda yadda yadda)
anyway, we have to find various informaiton about the planents. (orbital velocities, centripetal accelerations, etc.)
my...