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Homework Help: Fundamental Interactions Problem

  1. Aug 30, 2007 #1
    1. The problem statement, all variables and given/known data

    Imagine that I throw a ball toward the floor. It hits the floor and rebounds upward. What type of fundamental interaction between the atoms of the floor and the ball causes the ball to rebound upward?

    a. Strong nuclear
    b. Electromagnetic
    c. Weak nuclear
    d. Gravitational
    e. Some combination of the above
    f. Some other kind of interaction

    2. Relevant equations


    3. The attempt at a solution

    If the question is indeed only concerned with the rebound upward and not its descent, then I could first eliminate (d) gravitational interaction as a possible answer (I am not sure about this). Since this is a macroscopic interaction, I also eliminate (a) and (c). Because I am only left with (b) out of the above interactions, I can eliminate (e).

    If my reasoning is correct so far, the answer is either (b) or (f). It seems that the rebound upward would have something to do with a type of contact interaction--friction, compression, or tension. Is (d) still a possible answer, since if gravity were stronger, the ball could not rebound? If it is the case that all contact interactions are really just complicated electromagnetic interactions, should I confidently place (b) as my final answer?

    I cannot be confident about choosing any answer. Any help would be greatly appreciated.

    Last edited: Aug 30, 2007
  2. jcsd
  3. Aug 30, 2007 #2
    i say 'b'

    if I am correct, there are only 4 types of "fundamental interaction".
  4. Aug 30, 2007 #3
    Thanks for your reply, rootx.

    I am a bit confused about the question, because while it indeed asks for a type of fundamental interaction, of which there are only four, it presents the options: some other kind of interaction. Do the contact interactions I mentioned in my original post account for the rebound, and is it because that they are in fact electromagnetic interactions, that you have chosen (b) as your final answer?
  5. Aug 30, 2007 #4
    I thought of EM even before reading those provided options.
  6. Aug 30, 2007 #5
    Okay, thanks for your help.
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