Law of Attraction Warning !

Our galaxy, the Milky Way, contains approximately 4.02×10^11 stars with an average mass of 2.49×10^30 kg each. If the Andromeda Galaxy, our nearest neighbor, contains roughly the same number of stars and is 2.26×10^43 meters away, what is the gravitational force of attraction between the two galaxies?

I used the Law of Universal Gravitation.. but i’m getting different numbers everytime i punch them into my calculator.. please help?

Thanks!!

Assuming the average mass of stars in Andromeda is the same as the Milky Way
F = G(nm)^2R^2
F = 6.673 x 10^-11 x (4.02 x 10^11 x 2.49 x 10^30)^2/(2.26 x 10^43)^2 = 1.30 x 10^-13 N

To bring up something previously mentioned without addressing its proper name/title..

e.g. A satellite and the mass it is orbiting have an attraction to eachother. Newtons law of universal gravitation can be used to find the attraction of ’said’ masses.

Im not sure if that is grammatically correct any answers appreciated.

Yes you are correct.

Newton’s law of universal gravitation states that every particle in the Universe attracts every other particle. Write the exact mathematical expression for the force of attraction, and state in few words why this force of attraction is stronger between the moon and the earth than it is between you and your friend?
Thank you for answering my question! It made sense to me.

F = G (m1 . m2)/r^2

Since ‘G’ value is constant, I guess the reason here is my friend and I don’t have huge masses unlike moon and earth.

The hydrogen atom contains a proton and an electron seperated by about 5.0 x 10(-11) m. (the (-11) is supposed to be to the -11 power.)The mass of a proton is approx 1.7 x 10(-27) kg. (the (-27) means to the power of -27 also.) The mass of the electron is approx 9.0 x 10(-31)kg. (same thing as before(to the power)) The charge on a proton is 1.6 x 10(-19)C (same thing as before) and the charge on an electron is -1.6 x 10(-19) C.
Newton’s law of universal gravitation:
F(g)=(6.67 x 10(-11)power) x m1 x m2
(all this equation divided by r(2) (r squared)
Coulombs law:
F(e)=(9 x 10 (9) power) x q1 x q2
(all this equation divided by r(2) (r squared)
a) Use newtons law of universal gravitation to calculate the gravitational force between the electron and proton in the hydrogen atom.
b)Use Coulombs law to determine the force of attraction between the 2 particles.
c)Calculate the ratio between the electric force and the gravitational force. How import. are gravit. forces in this case?

Come on now this is a common sample problem to show you how the Coulomb force is so much LARGER than the gravitational force. You should do it yourself. It’s a matter a plugging in the Numbers in Coulomb’s Eq and then into Newton’s and forming a ratio.

It will show you that Gravitational forces are unimportant when calculation electrical forces between charged particles.

According to the law of universal gravitation, the force of gravitational attraction increases directly as two masses increase, and decreases in proportion to the square of the distance between the two masses. What happens to the force of gravitational attraction between the two bodies of equal mass if:

The distance between the two objects is doubled?

Can anyone please provide an explanation as to how they found the answer. This should be easy for physics geeks. Just to let you know I suck at physics, so type like a baby types when explaining.

Dear Vulcan#3,
If all you are dealing with is a change of distance between two gravitationally attracted objects… then just deal with the change in distance! : If you double the distance (and the masses are unchanged) the grav. attrctn will be one-quarter as strong. It is the rule of inverse squares: Double the distance and the force is 1/4. Triple the distance and the force is 1/9. Halve the distance and the attraction is 4x as strong…
‘Hope this appropriately addresses your question.