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Gravitational force multiple choice question

  1. Dec 6, 2008 #1
    1. The problem statement, all variables and given/known data
    Which of the following is a correct statement about gravitational force?
    A. It is applicable only to our solar system.
    B. It is both an attractive and repulsive force.
    C. It is directly proportional to the product of the masses involved.
    D. It is directly proportional to both the mass and radius of the earth.

    3. The attempt at a solution
    The answer I got for this question is "C" because it seems to be the most correct out of the four possible choices but I was just wondering I am correct because:


    A) It cannot only be applicable to our solar system because we have not yet discovered or know enough of other solar systems to make this assumption therefore "A" is wrong.

    B)Gravitational force is defined as an attractive force emitted by particles that attracts other particles, so therefore I am guessing, it cannot be a repulsive force therefore "B" is wrong.

    However I have heard somewhere that a gravitational force that is repulsive does exist in dark matter, so I was just wondering if this could make "B" correct?

    C)Is what I guess to be right.

    D)Gravitational force exists on other planets also, therefore it cannot be possible that it is directly proportional to both the mass and radius of Earth in every case, so "D" is wrong.
  2. jcsd
  3. Dec 6, 2008 #2


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    Homework Helper

    Your choice is correct.
  4. Dec 6, 2008 #3
    I just have one question, I just happened upon a site that has the exact same question with the exact same choices and what they put as the correct answer is "D". I was just wondering if "D" is really the correct answer and why it is if it is the correct choice? Thanks for your help though, I really appreciate it.
  5. Dec 7, 2008 #4
    Problem I have with answer D being right is that I would assume "gravity force" is a general term, not Earth specific.

    Secondly, it should be inversely proportional, as the gravity force goes down as you go farther out from the center of gravity, or in other words, having a larger Earth radius.
  6. Dec 8, 2008 #5
    Now that you mention it, yeah that would be another reason why "D" should not be the right answer.

    I know that this is a multiple choice question and that there is only one right answer (and the answer is apparently "D" for some strange reason) but I chose choice "C" would choosing "C" for an answer be correct still or is "C" incorrect for this question?
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