What is the force exerted by the shuttle-rocket engines during launch?

[map7s]

Homework Statement

NASA launches a shuttle with a mass (including the rockets) of 1.81 x10^6 kg. If it accelerates upward at a rate of 13 m/s2 near the Earth's surface, what is the force that the shuttle-rocket engines exert? (Of course, the shuttle does not actually have this much acceleration until it is well above the Earth's surface, but that is a harder calculation!)

Homework Equations

F=ma

The Attempt at a Solution

Is there another equation that I should use in this problem? because I was thinking that I have the mass of the entire shuttle and the acceleration at that point, so I could just plug that into the equation to solve for mass. I also tried using a free-body diagram in case I was missing anything, and then I saw that weight would play a part in this process, so then I tried F=ma-mg but I'm still having difficulty figuring out the right answer.

 

[map7s]

never mind...I figured it out...

 

[G01]

Remember that Newton's second law reads like this (pay attention to the sigma):

\Sigma\vec{F}=m\vec{a}

So, what you will find is the net force if you find ma. What forces make up this net force?

 

[G01]

never mind...I figured it out...

Awesome!