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Starting from rest several toy cars roll down ramps at different

  1. Feb 29, 2008 #1
    Starting from rest several toy cars roll down ramps at different lengths and angles. Rank them according to their speed at the bottom of the ramp from slowest to fastest. Car A goes down a 10m ramp inclined at 15 degrees, Car B goes down a 10 m ramp inclined at 20 degrees, car C goes down a 8 m ramp inclined at 20 degrees and Car D coes down a 12 m ramp inclines at 12.
  2. jcsd
  3. Feb 29, 2008 #2
    Welcome to PF.
    Velocity at the bottom of an incline is independent of angle of inclination and length of inclines.
  4. Feb 29, 2008 #3
    thank you
  5. Feb 29, 2008 #4
    Always Game.
  6. Feb 29, 2008 #5
    ? Can you explain?
  7. Feb 29, 2008 #6


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    (physixguru means length as opposed to height.)

    Hint: this follows from conservation of energy - can you see why?

    Also, don't forget that that's only half the problem: the speed immediately after leaving the ramp (on the horizontal ground) is a lot less than the speed immediately before leaving the ramp (that's pretty obvious if the ramp is almost vertical, but it's still true for small angles). :smile:
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