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Homework Help: Finding the upward force acting on an object

  1. Feb 23, 2009 #1
    1. The problem statement, all variables and given/known data

    A spaceship is accelerating upwards with an acceleration of 0.50g. It's mass is 2.0 x 10⁶ kg. What is the upward force this object is exerting?

    2. Relevant equations
    Fnet = ma
    Fnet = Sum of all forces.

    3. The attempt at a solution
    A = 4.9 m/s² [up]
    g = 9.8 m/s² [down]
    m = 2.0*10⁶ kg.

    I plugged it into the Fnet = ma. So:
    Fnet = (2.0*10⁶ kg)(4.9 m/s² [up])
    = 9800000 N [up]

    Then, I found the force of gravity acting on the object... It just would be 2(9800000 N) because the acceleration I just used was half that of gravity. The force of gravity acting on the object would be 19600000 N [down].

    So: Fnet = Fup + Fg
    9800000 N = Fup +(-19600000 N)
    9800000 N = Fup - 19600000 N
    Fup = 9800000 N + 19600000 N
    = 29400000 N [up]
    = 2.9 * 10⁷ N [up]

    Can anyone let me know if I did this correctly or if I am totally off?

  2. jcsd
  3. Feb 23, 2009 #2


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    Homework Helper

    Since you are using the word upward I would have to agree that gravity is involved.

    If it is moving against gravity, then isn't it simply

    F = m*a = m*(g + .5g) = 3/2*m*g ?

    This apparently agrees with your result.
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