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Homework Help: Acceleration of two masses and tension.

  1. Oct 13, 2009 #1
    1. The problem statement, all variables and given/known data
    Hi guys, got a bit of a tough problem that i cant seem to solve.

    What is the acceleration of two masses and the tension in the string if both surfaces are friction less.

    http://img376.imageshack.us/img376/5889/physics.jpg [Broken]

    2. Relevant equations

    3. The attempt at a solution

    Now i had another example that i tried to follow but, in that one the force of friction is 9N. I tried to make the following eqn

    m2a = -T-m2gsin40 - ( this is where i got stuck, i dont know what to subtract as there is no force given.)

    could someone give me an idea where to start? thanks.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Oct 13, 2009 #2
    Think about (and set up) your free body diagram. You know that tension is an internal force (i.e. it doesn't happen by itself, something causes tension). And you know your system is isolated. Just imagine intuitively, what's stopping the 5kg block from sliding down the ramp if the ramp is very slippery? Is there anything stopping it?

    It might also be helpful to think about this system as two dangling weights (i.e. with no surface, therefore no friction) and then think about what the surface does.
  4. Oct 13, 2009 #3
    Him ok so i dont know if this is right but i was able to find out FN by doing this

    FN = mg x cos[tex]\vartheta[/tex] = 3kg(9.8m/s2) * cos30
    FN = 42.43N

    Now from here would i go on to find T1 for the 3kg mass?
    Last edited: Oct 13, 2009
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