Questions: about the force of gravity.

1. Jul 4, 2008

Katt

1. The problem statement, all variables and given/known data

I have two questions (stated below), but do not feel confident about my answers:

(1)Which of the following statements about the force of gravity is false?
a. it is a universal force, which acts everywhere in space
b. its strength decreases as the square of the distance
c. its strength is inversely proportional to the mass: the more mass, the less gravity
d. the force never becomes zero
e. it causes the paths of the planet to be ellipses and not straight lines.

(2) Newton's Law of Gravity, the force of gravity goes up as the:

a. mass goes down
b. mass goes up
c. distance does down
d. distance goes up
e. or more than one of the above

3. The attempt at a solution

For the first problem I think c. is false because I thought the more mass you have the more gravity there is.
For problem (2), I think, "the force of gravity goes up" as the, (d.)distance goes down.

However, I am not sure. Hopefully, you can inform me on the correct answer.

(My apologies, if I am posting in the wrong section).

2. Jul 5, 2008

Vagrant

Both the questions can be answered by considering G= g M m/ r^2

3. Jul 5, 2008

Staff: Mentor

1d is for mindreaders, it depends on what kind of answer teacher wants to hear.

4. Jul 5, 2008

WARLORDTF

Upon my knowledge the mass of an object is derived from intermolecular forces called higgs boson, where the P+ and N give and receive a 'force' (probably the wrong word but...) which gives the atom mass the gravitons present in the atom makes the mass of the object react to gravity.
This probably didn't help much but is my input, which i find isreasonably good considering i am in yr 10 of schooling :rofl:

5. Jul 5, 2008

Katt

Thanks for the help, but I am still confused.
For the first problem, I was trying to see which problems were true statements, thus leaving 1 false one left.

This is where I am so far:
- I read that, " Gravity can never become zero. We can increase the separation and make the force as small as we like, but we can’t make it go away." So, d cannot be the false statement.

- "It is a Universal force that acts everywhere in space," is a true statement too. So, I think that (a) cannot be the false statement.

- "It causes the planets to be ellipses and not straight lines," is also true and not false.

So, if I am correct that leaves me with either (b) or (c) as the false statement, I do not not which one it is though.

6. Jul 5, 2008

Staff: Mentor

Does it have to be one false answer? You posted confusing "statements is" phrase.

Take a look at the equation posted bu Shramana, it will tell you whether c is OK.

7. Jul 5, 2008

Katt

For the first problem: I have to find the statement that is false.
There is only 1 false statement out of the 5 choices listed.

So, I think c is the answer to problem(1) because it says "the more mass, the less gravity." That contradicts what I have read, which states, the more mass something has the greater the gravity. C must be the false statement and the other statements must be correct.

???

8. Jul 5, 2008

Staff: Mentor

C it is then.

9. Jul 5, 2008

Katt

Ok!... So, that would mean for problem(2), that the force of gravity goes up as the, "mass goes up," all of which effects the distance...

10. Jul 5, 2008

Staff: Mentor

The higher the mass, the stronger the gravity. That's true, but that's not all.

11. Jul 5, 2008

Katt

Let me try this again!
The force of gravity goes up as the "mass goes up" and,
the force of gravity goes up as the, "distance goes down" because gravity increases as the distance decreases.

12. Jul 5, 2008

Hootenanny

Staff Emeritus
Sounds good to me

13. Jul 5, 2008

Katt

Finally, I get it. Thanks everyone for the help.