# Homework Help: Finding the upward force acting on an object

1. Feb 23, 2009

### shootingrubbe

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. Feb 23, 2009

### LowlyPion

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.