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Homework Help: Conservation of energy and height of projectile

  1. Oct 11, 2006 #1
    A child slides without friction from a height h along a curved water slide (Fig. P5.44). She is launched from a height h/5 into the pool. Determine her maximum airborne height y in terms of h and . (Use q for and h as appropriate.)
    p5_44.gif
    I understand that you use conservation of energy to solve the problem, but for some reason my brain is dead to physics today. O-chem/Calc 1/Bio I can handle but for some reason these word problems are really tripping me up.

    Here's what I have so far.

    W(nc) =(KEf + PEf) - (KEi + PEi)
    0 = 1/2mv^2 + mg(h/5) - (0 + mgh) (For the end of the slide to find velocity when she leaves slide)
    ymax = vo^2sin^2(q) /(2 g)

    Am I on the right track?
     
  2. jcsd
  3. Oct 11, 2006 #2
    yes it is looking good, except i think you have some typo's in the last equation line, but i know what you mean.
     
  4. Oct 11, 2006 #3
    I ended up with ymax = (-h/5 + h)*(sin(q))^2 and its registering as incorrect. Notice any errors?
     
  5. Oct 11, 2006 #4
    how did you get (-h/5 + h)? I'm not getting that from using the energy equation solving for v.
     
  6. Jan 8, 2009 #5
    u've got it wrong- it's conservative since it's frictionless
     
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