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Homework Help: Interesting torque problem!

  1. Nov 20, 2012 #1
    1. The problem statement, all variables and given/known data

    In procedure 3, you balance the ruler. If the density of the ruler increases without changing its dimensions, the ruler will...

    →still be balanced
    →be unbalanced, but the direction depends on the hanging mass, the mass of the ruler, and distances
    →tip away from m
    →tip toward m

    In my lab report, it says that I need to balance the ruler at the 40 cm mark and then, adjust the mass to the left to make the ruler balanced.

    2. The attempt at a solution

    I said that the ruler will tip away from m, contrast to the ruler hung at the center 50 cm mark, but I'm not sure if that is true.
  2. jcsd
  3. Nov 21, 2012 #2


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    Replace the ruler with massless ruler and an equivalent mass hanging from its center of gravity.
    Last edited: Nov 21, 2012
  4. Nov 21, 2012 #3
    The centre of gravity will not move to another point when its density is increased - look at the formula for calculating the coordinates of the centre of gravity - this is what CWatters suggests in effect just worded differently.
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