# Force Inverse square law

1. Jul 18, 2011

### berge616

I am confused regarding the following question. My guess is that b is correct, because the gravitational force equation has r^2. However beyond that I am not sure if any other options are correct. Please help

What do you know about a force that follows the inverse square law.
(a) The force is strong.
(b) The force decreases with distance.
(c) The force depends on the magnitude of the masses involved.
(d) The force depends on the magnitude of the charges involved.
(e) The force depends on a universal constant.

2. Jul 18, 2011

### WannabeNewton

You are correct in saying it is (b). (a) does not say anything in general about the law, (c) and (d) can be ruled out by giving coulomb's law and newton's law respectively and (e) can be ruled out by using as an example the inverse square law that determines the intensity of radiation, emitted at a point source and distributed spherically, at a distance r from the source which does not include any universal constant. (b) is part of the definition of an inverse square law.

3. Jul 19, 2011

### mathman

Newton's law: F=Gm1m2/r2, where the m's are the masses involved, r is the separation, and G is a universal constant. Therefore b, c, and e are all correct.

4. Jul 19, 2011

### WannabeNewton

The question is asking about inverse square laws in general though. (c) and (e) are not general cases.

Last edited: Jul 19, 2011
5. Jul 20, 2011

### mathman

The question is very badly worded.