No Earth, No Gravity: What Would it Be?

[cdux]

If there was no earth, what would be the acceleration of gravity from here from the Sun?

 

[jedishrfu]

This is a fairly simple thing to figure out. Is this for a homework assignment?

Get on wikipedia find the the mass of the sun and go from there.

 

[cdux]

It's not but I realize it's easy to find out:D Nevermind.

 

[jedishrfu]

the mass of the sun is in the first 5 lines of the article:

http://en.wikipedia.org/wiki/Sun

 

[marcus]

Two easy things to remember: distance to sun ≈ 150 million km
earth orbital speed ≈ 30 km/second.

v²/R
=============

of course our distance to sun changes by a few percent during the year. the Earth orbit is not perfectly circular. so the acceleration due to sun gravity at this distance is going to change a little.

=============

I would bet this is not homework, just someone who is curious.

You could use Google calculator too. It knows "mass of sun" and it knowns "G" the Newton gravitational constant and it knows "AU" the astronomical unit (mean distance to sun).

So probably you could type into google window "G*mass of sun/(AU^2)" and get it.

Yeah, when I do that it says 0.006 m/s^2
=================

But if I didn't have google calculator handy I think I would use "v-squared over R"
I wouldn't go looking up the mass of the sun, and Newton's G constant.
I would just say v = 3 x 10⁴ m/s
so then v² = 9 x 10⁸ m²/s²

And then I would divide by R = 1.5 x 10¹¹ meters

 

[cdux]

I'm surprised it's so low compared to earth's. Then again, the Earth's diminishes rapidly out of low orbit.

 

[marcus]

Well it's good to be surprised, so that's good. But a propos what you said about Earth gravity, and practice using google calculator

what would be the acceleration to the Earth at the distance the moon is?