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Homework Help: Confusing (but surely simple) gravity problem

  1. Apr 5, 2008 #1
    1. The problem statement, all variables and given/known data

    An exceptional vertical jump from rest would raise a person 0.80m off the ground. To do this, what constant force would a 70kg person have to exert against the ground? Assume the person lowers himself 0.20m prior to jumping and remains in a standing position while in the air.

    2. Relevant equations

    F(net)=ma?


    3. The attempt at a solution

    Not a clue...
     
  2. jcsd
  3. Apr 6, 2008 #2
    It's easy to say: "Not a clue..." :smile:

    Maybe https://www.physicsforums.com/showthread.php?t=225490" will help (as it already did). It's almost the same.

    You need the velocity at which man must leave the ground to reach the height of 0.8 m (you know the g). Therefore you can calculate the acceleration and the force.
     
    Last edited by a moderator: Apr 23, 2017
  4. Apr 6, 2008 #3
    Lol, thank you soooo much (again!)
     
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