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Homework Help: Objects on a Slope - Pretty Easy

  1. Oct 16, 2008 #1
    Objects on a Slope -- Pretty Easy

    This is a modified version of a physics problem for my HW. We were to find the mass an item had to be to "go down" a slope and go up. However, the slopes were not even so a larger mass one side did not necessarily mean the "heavier" side slid down.

    So I made another problem where they were even. In this case it was 60 degrees.

    The slope is 60 degrees. The mass on the left Fl is 2.1 kg. My hypothesis is that a larger mass is required on the right to make the right "go down" or have a positive acceleration. Correct?

    Here's my Force equation.

    Ftotal = Fl + Fr.

    I picked a random number, .64 m/s2 for the right acceleration to be.

    sin(60)(.64)m = (9.8)m + sin(60)(2.1kg)(-9.8)
    which leads to m = 1.86 kg, which is obviously wrong!

    Where did I go wrong? If I solve for a negative acceleration, I at least get a number less than 1.86 which makes logical sense at least. Any ideas on what I did wrong?
  2. jcsd
  3. Oct 17, 2008 #2
    Re: Objects on a Slope -- Pretty Easy

    Are the two objects connected by a rope or something?
    Your "presentation" of the problem is very vague and confusing.
    You probably know very well what is it about (I hope) but you cannot expect other people to guess your mind.
    This is a physics forum (and not psychic forum).
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