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Sliding ice

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

    A block of ice with mass 2.00kg slides 0.750m down an inclined plane that slopes downward at an angle of 36.9degrees below the horizontal.

    f the block of ice starts from rest, what is its final speed? You can ignore friction.

    2. Relevant equations

    F=ma, trig equations.

    3. The attempt at a solution

    not really sure how to tackle this one.
    i have initial velocity of 0, angle, mass and distance, but i can't figure out how to tie it all together.

    should i be tackling it one dimension at a time? seeing as i know the vertical acceleration and angle?
  2. jcsd
  3. Aug 30, 2007 #2


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    Find the component of the downward force (weight) in the direction of the slope.
    Then just f=ma to get the acceleration and v^2 = u^2 + 2as to get final speed.

    Or from conservation of energy. Find the vertical distance equivalent to 0.75m at 36.9deg
    then use PE = mgh = KE = 1/2 mV^2
  4. Aug 30, 2007 #3
    sweet thanks heaps.
    used the conservation formula and got 2.97m/s which was correct.
  5. Aug 30, 2007 #4


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    My tip is to always use energy conservation if you can. It's a lot simpler than getting all the forces in the right directions and less prone to errors.
  6. Aug 30, 2007 #5
    I always use that work-energy equation. (Assuming that there's nothing like potential energy)

    I guess, energy conservation can sometimes put you in trouble.
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