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Homework Help: Four 100 kg people are holding a 1200 kg inflated balloon

  1. Feb 17, 2013 #1
    four 100 kg people are holding a 1200 kg inflated balloon by means of four ropes. three people let go and the balloon accelerates upward at 2 m/ s/s. what is the tension in the rope the last person is holding?
  2. jcsd
  3. Feb 17, 2013 #2
    What are your ideas on this?
  4. Feb 17, 2013 #3
  5. Feb 17, 2013 #4
    These are the 2 forces on the person, but if they were equal then the person would have an acceleration of zero.

    Apply Newton's second law to the person.
  6. Feb 17, 2013 #5
    ma=mg where a = 2 so m(a-g)=0 so 800 but I know it's actually a+g so 1200 why?
  7. Feb 17, 2013 #6
    ma = mg is not correct.

    Newton 2 says that the total force on the person = ma
    You've written the total force as just mg. You need to include the tension in here as well.

    Just draw a quick diagram showing the forces on the person and the direction of the acceleration and then apply Newton 2, ( and be careful with the signs ).
  8. Feb 17, 2013 #7
    oh! thank you very much
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