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Speed, distance and spring on a track

  1. Jun 7, 2009 #1
    1. The problem statement, all variables and given/known data

    Tarzan (m=90kg) presses against a horizontal spring with spring constant k=81000N/m ( on a frictionless surface), compressing it by 100 cm. After loosing contact with the spring, Tarzan starts going down an 11.0 m high hill that is frictionless, and then starts to go up a frictionless incline of 30o on the other side. How far along the slope will Tarzan get?
    Picture can be found here https://www.physicsforums.com/showthread.php?t=315325"

    2. Relevant equations

    e=0.5mv2
    eg=mgh
    spring = 0.5kx2

    3. The attempt at a solution

    this question very similar to a previous question i posted but i can not seem to carry it forward and find the distance the person would travel it they went up the hill of the frictionless hill. i first found the speed which was 30 m/s. since the track is frictionless i assummed the speed would be the same and set up and another equation 0.5mv2=mgh where h= dsin[tex]\vartheta[/tex] and i solved for d this didnt work out ..pls. help
     
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Jun 7, 2009 #2
    The speed wouldn't be the same all along the track. Tarzan accelerates down the hill and decelerates up the ramp.
     
  4. Jun 7, 2009 #3
    so do i find the acceleration of the person using a kinematic equation where the acclerration is gravity - x. x being the deceleration>>??
     
  5. Jun 7, 2009 #4

    dx

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    Use conservation of energy. Acceleration is not needed here.
     
  6. Jun 8, 2009 #5
    if i used conservation of energy then wouldn't this be right 0.5mv2=mgh where h= dsin[tex]\vartheta[/tex]
     
  7. Jun 8, 2009 #6

    dx

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    You forgot the initial gravitational potential energy. Also, you dont need to calculate initial velocity. Just use the spring potential energy.
     
    Last edited: Jun 8, 2009
  8. Jun 8, 2009 #7
    so then wld it look like mghinitial+0.5*kx2= mgdsin[tex]\vartheta[/tex]...where hinitial= 11m ??
     
  9. Jun 8, 2009 #8

    dx

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    correct.
     
  10. Jun 8, 2009 #9
    thanks :)
     
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