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General Physics Help

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  1. Mar 11, 2016 #1
    1. The problem statement, all variables and given/known data
    A rocket of force 1000N is propelled upwards by a thrust of 1800N. The air resistance is 500N.

    a) Work out the resultant force on the rocket.

    A bungee jumper of mass 60kg jumps from a bridge tied to an elastic rope which becomes taut after he falls 10m. Consider the jumper when he has fallen another 10m and is traveling at 15 m/s.

    A) Work out how much energy is stored in the rope. Take g= 10 m/s squared and ignore air resistance.

    2. Relevant equations

    E = mgh
    3. The attempt at a solution
    1)a)
    1000N+1800N - 500N = 2300N

    2)a)
    60*10*10 = 6000J
     
    Last edited: Mar 11, 2016
  2. jcsd
  3. Mar 11, 2016 #2

    haruspex

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    It says "a rocket of 1000N". What do you think that means?

    Edit: please use a separate thread per problem.
     
  4. Mar 11, 2016 #3
    I meant force! And sorry, I'll do that next time.
     
  5. Mar 11, 2016 #4

    haruspex

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    No, surely the 1800N is the thrust. Isn't the 1000N the weight?
     
  6. Mar 12, 2016 #5
    I checked the question in my book and yes, it is weight. I am really sorry.
     
  7. Mar 12, 2016 #6

    haruspex

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    So how does that change your equation?
     
  8. Mar 12, 2016 #7
    The equation e= mgh is for the second question. The answer to the first question is 300N, but I am not understanding why.
     
  9. Mar 12, 2016 #8

    haruspex

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    I mean this equation
     
  10. Mar 13, 2016 #9
    I looked into it and I understood now, thanks for the help.
     
  11. Mar 13, 2016 #10
    For the second one if I am not mistaken would one not have to use gravitational potential energy and kinetic energy to find the amount of energy that was transferred to the rope?
     
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