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People jumping in the air simultaneously

  1. Nov 21, 2006 #1
    2. If 270 million people in the United States jumped up in the air simultaneously, pushing of Earth with an average force of 800N each for a time of 0.10s, what would happen to the 5.98 x 1024 kg Earth?

    And this is what i wrote:
    Basically why I did was try to find out the velocity, to see if the earth moves from the force applied. So by identifying the variable needed for ft=▲mv, I get
    800(.1)= 5980000000000000000000000x. Leaving me with 80/5980000000000000000000000, leaving me with the velocity of 1.3 m/s. Therefore when 270 million people jump at the same time the earth will move at 1.3 m/s.

    is this right?
     
    Last edited: Nov 21, 2006
  2. jcsd
  3. Nov 21, 2006 #2

    radou

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    How did you get that huge number? Doesn't it say there's a 800 N force from every person? So, the impulse of the net force should equal 800 * 270 * 10^6 * 0.1, shouldn't it?
     
  4. Nov 21, 2006 #3
    yea but i thought it was focusing on the earth and she gave me...oh wait the question didnt paste into the topic correctly....its supposed to be 5.98x10 with and exponent of 24

    thats where i got that big numba lol
     
  5. Nov 21, 2006 #4

    radou

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    Yes, I'm aware of that. :smile:
     
  6. Nov 21, 2006 #5
    than doesnt 5.98x10to the 24 equal 5980000000000000000000000?
     
  7. Nov 21, 2006 #6

    radou

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    Yes, it does. (I didn't count the zeroes, though. :biggrin:) Anyway, it is practical to write the same number as 5.98 x 10^24.

    Anyway, that's the mass of the Earth. But the relevant thing is the fact that you multiplied 800 with 0.1 only. That is the average force exerted on the Earth by one person only.
     
  8. Nov 21, 2006 #7
    ohh yea so then the net force would have been 80x270,000,000
     
  9. Nov 21, 2006 #8
    so now my answer would be:

    Therefore when 270 million people jump at the same time the earth will move at 276851851851851.85 m/s.
     
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