Question

Suppose earth were moved to a distance from the sun equal to 4 AU. How much weaker would the sun's gravitational force on earth be? Why?

Answer 1

Do you know Newton's Law of Universal Gravitation?

Answer 2

No I actually don't. I just don't get astronomy at all!

Answer 3

@Shane_B

Answer 4

Newton's Law of Universal Gravitation provides the following equation for the force between two objects:\[F=G\frac{m_1m2}{r^2}\]G is the gravitational constant, m1 and m2 are the objects and r is the distance between them.

Looking at the equation you should see that the force is inversely proportional to the square of the distance between the objects. So if you increase the distance (r) between them by a factor of 4, the force of gravity between them would decrease by 4^2...so 16 times less than it was before.

Answer 5

So would 16 times less be the new gravitational force the sun has on the earth or would that only be part of the equation?

Answer 6

Yes. It would be 1/16th of the force it had before.

Answer 7

And why would it be weaker? Is it because the earth is now farther away being how the distance is 4 AU compared to it normally being 1 AU? And is there a scientific explanation for that?

Answer 8

I think you got it. It's weaker because the distance has increased from 1AU to 4AU. The explanation I guess would be Newton's Law of Universal Gravitation.

You should also consider what would happen if the physics of the universe worked the opposite way: If the force of attraction between two objects got stronger as they got closer together everything would crash together and we wouldn't be here talking about it.

Answer 9

Thank you so much! I really appreciate it(:

Answer 10

no problem :)