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Homework Help: Work and Energy Problems- Please help!

  1. Nov 3, 2009 #1
    1. A spring has a force constant of 30000 N/m.
    How far must it be stretched for its poten-
    tial energy to be 47 J?
    Answer in units of m.

    2. A bobsled slides down an ice track starting
    (at zero initial speed) from the top of a(n)
    94.5 m high hill.
    The acceleration of gravity is 9.8 m/s2 .
    Neglect friction and air resistance and de-
    termine the bobsled’s speed at the bottom of
    the hill.
    Answer in units of m/s.

    3. An ore car of mass 40000 kg starts from rest
    and rolls downhill on tracks from a mine. At
    the end of the tracks, 9.4 m lower vertically,
    is a horizontally situated spring with constant
    4.5 × 105 N/m.
    The acceleration of gravity is 9.8 m/s2 .
    Ignore friction.
    How much is the spring compressed in stop-
    ping the ore car?
    Answer in units of m.

    4. A roller coaster cart ofmassm = 336 kg starts
    stationary at point A, where h1 = 27.7 m and
    a while later is at B, where h2 = 13.3 m.
    The acceleration of gravity is 9.8 m/s2 .
    What is the speed of the cart at B, ignoring
    the effect of friction?
    Answer in units of m/s.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
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