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Homework Help: Which ones faster?

  1. Dec 17, 2007 #1
    THeres this question on my homework that asks if the mass was doubled would the object slide down the wall faster than the original mass. I said yes it would, but then I caluculated the friction of both and the doubled mass has a larger friction wouldn't that make it slower?
  2. jcsd
  3. Dec 17, 2007 #2


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    What is the full problem statement?

    Does it say to ignore air resistance, friction, etc...?
  4. Dec 17, 2007 #3
    Is the wall perpendicular to a flat ground? If so, think about what would happen if you dropped an object against the wall; for there to be a force of friction there must be a normal force on the object from the wall, and if there is a normal force against the object perpendicular to its motion, the object will either accelerate away from the wall for the brief instant the object is in contact with the wall, or else there must be some other force keeping the object pushed up against the wall. Does this other force exist?
  5. Dec 18, 2007 #4

    Shooting Star

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    I feel that the OP meant a mass sliding down an inclined plane, in which case the force along the plane is ma = mgsin(theta) – kmgcos(theta), and so the accn is independent of the mass. This applies to the vertical wall as well. But of course only the OP can give us the actual problem.
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