# Thread: im sorry but i think universal gravitation formula is wrong

1. the sun appears the same size of the moon cause its 400 times farther and 400 times bigger, earth is 3.7 times bigger than the moon

my premise is that an object is in orbit cause centrifugal force is equal to the atraction on the mean orbit, im supposing orbits perfectly rounded for simplification reasons

mass of the moon= x distance earth moon =y
mass of the sun 400x distance sun earth 400y

mass of earth 3.7x

w of the moon around the earth= 13z w of the earth around the sun= z

so lets 1st find out gravitational force of the sun and earth:

F=400x*3.7x/(400*400*y*y)=1*10e-3 (x*x)/(y*y)

now lets find gravitational force moon earth=

F=3.7x*x/(y*y)=3.7(x*x)/(y*y)

so you can see the gravitational force is much greater for the moon earth

therefore centrifugal force should be much greater on the moon around the earth than in the earth around the sun lets find if its true:

centrifugal force of the earth around the sun

Fc=m*w*w*r
F=3.7x*z*z*400y=1480x*z*z*y

centrifugal force of the moon around the earth:

f=x*13z*13z*y=169x*z*z*y

so you can see the earths orbit has much greater centrifugal force spining around the sun than the moon spinning around the earth

this arises a simple question:

how can be centrifugal force of earths orbit around the sun be much greater than moons orbit around the earth and force of atraction be the oposite, be much much stronger for the moon orbit than for the earth orbit

in a circular orbit both centrifugal force and force of gravity are exactly equal, if one doubles so does the other

in an eccentric orbit both centrifugal force and force of gravity will be equal in the mean radius  2.

3. Originally Posted by luxtpm
mass of the moon= x distance earth moon =y
mass of the sun 400x distance sun earth 400y
How do you figure the mass of the sun is only 400 times the mass of the moon?  4. oh thanks a lot for this hint ill make the calculation again  5. the thing is that im trying to obtain the universal gravitation formula using centrifugal force but i keep finding odd things, the first:

supposing moon mass = x, sun mass will be 400*400*400x and earth mass 3.7*3.7*3.7 x

earth moon distance is y and sun earth distance 400 y

lets find force of gravity for each

earth moon:

F=3.7*3.7*3.7x*x/(y*y)=50 x*x/(y*y)

sun earth:

400*400*400x*3.7*3.7*3.7x/(400*400*y*y)=20261 x*x(y*y)

so being so much stronger gravitation of the sun on earth than the moon on earth how comes tides are mainly caused by the moon?  6. yes thanks harold with your hint i manged to balance centrifugal force with gravity approximately

and i wont bother to try to understand tides, thats beyond my limit  7. okay. I'll give you a slight bit of help on tides. Think of it this way, how does the force of the sun change on the surface of the earth, i.e. whats the change in the force for a movement along our surface, from the side facing the sun to the side away from the sun. Remember, we are about 92-94 million miles away.  8. now from my other thread now you know i do believe universal gravitational formula

but i prefer to believe my personal experience to what im told  Bookmarks
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