1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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?

    Thanks.
     
  2. jcsd
  3. Feb 23, 2009 #2

    LowlyPion

    User Avatar
    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.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook