Question

Object A attracts object B with a gravitational force of 10 newtons from a given distance. If the distance between the two objects is doubled, what is the changed force of attraction between them?
Choices are here: http://i37.servimg.com/u/f37/16/73/53/52/choice11.png

Answer 1

Do you know the equation for gravitational force?

Answer 2

Isn't it F=Gm1m2/r2

Answer 3

\[F=G\frac{m_1\ m_2}{d^2}\]

Double the distance, and what happens? So, \(d\) becomes doubled: \(2d\). Put \(2d\) in the place of \(d\) for your new force. Then compare the two! That's how all of these problems go..

Answer 4

Oh okay

Answer 5

\[F_2=G\frac{m_1\ m_2}{(2d)^2}=G\frac{m_1\ m_2}{2^2d^2}=G\frac{m_1\ m_2}{d^2}\frac{1}{2^2}\\=G\frac{m_1\ m_2}{d^2}\frac{1}{4}\]And since\[F=G\frac{m_1\ m_2}{d^2}\]you can substitute to see that\[F_2=F\frac{1}{4}\]
\(F_2\) is \(\frac{1}{4}F\), and \(F=10\ [N]\). So, I think you can handle it from here.

Answer 6

So.. 20 Newtons..it is

Answer 7

Why?

Answer 8

Substitute \(10\ [N]\) in for \(F\) to find \(F_2\)! I did that algebra, so it's right :P

Well, I'm not always right, but that is.

Answer 9

You are majority of the time~

Answer 10

Haha, thanks. And I don't think it's \(20\ [N]\)...

Answer 11

It isn't? o.o Because I got it right....

Answer 12

But then again, some of the questions/choices from my online class have been wrong before..

Answer 13

According to information I've looked up on them and calculated at times

Answer 14

Oh, Cool! I would've guessed \(2.5\ [N]\).

Answer 15

I still think that's right...

Answer 16

\[F_2=10\ [N]\frac{1}{4}=2.5\ [N]\]

Answer 17

That's weird....

Answer 18

its 2.5 i pick 20 got it wrong then i pick 2.5 and got it right