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Homework Help: Rocket Motion Problem

  1. Apr 7, 2010 #1
    1. The problem statement, all variables and given/known data
    What is the acceleration of the rocket at a time of 5seconds after the parachute opens.


    2. Relevant equations
    F=ma


    3. The attempt at a solution
    I simply thought the acceleration would be 9.8m/s/s
     

    Attached Files:

  2. jcsd
  3. Apr 7, 2010 #2

    Mark44

    Staff: Mentor

    That would be the acceleration acting downward if there were no parachute. The retarding force R of the parachute acts upward, in the opposite direction of the gravitational force acting on the rocket.
     
  4. Apr 7, 2010 #3
    You also have to take into consideration the resistance force on the parachute; that will affect the acceleration.
     
  5. Apr 7, 2010 #4
    so the resistance force of the parachute is 1.8N. So I know its going to be F-1.8=mass(which I forgot to mention but its 0.2kg) * acceleration., But how do I calculate the upwards acceleration
     
  6. Apr 7, 2010 #5

    Mark44

    Staff: Mentor

    F = ma, so a = F/m. What's the net acceleration, and in what direction?
     
  7. Apr 7, 2010 #6
    would the net acceleration be 1.8/0.2?
     
  8. Apr 8, 2010 #7

    Mark44

    Staff: Mentor

    No, that's the acceleration upward. The net acceleration would be the vector sum of the upward and downward accelerations.
     
  9. Apr 8, 2010 #8
    ohh so a=(9.8-1.8)/0.2
     
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