Physics 11 Net force and Acceleration

[anOldMan]

Homework Statement

g=10m/s^2
A fully loaded Saturn rocket has a mass of 2.92x10^6kg. Its engines have a thrust of 3.34x10^7N.

a) How much does the rocket weigh. answer 2.92x10^7 N
b) What is the net force on the rocket when it blasts off? answer 4.2x10^6N
c) What is the acceleration as it leaves the launch pad? 144m/s^2
d) What is its speed after 60 seconds? answer 86.4m/s
e) As the rocket moves away, the engine thrust is constant but the mass decreases - why? What effect does this have on acceleration. answer Fuel is consumed; m decreases, a increases.

Homework Equations

F=ma P.E. =mgh

The Attempt at a Solution

I have no idea how the answer for b) becomes 4.2x10^6N
Any help would be appreciated.

 

[anOldMan]

Part c

Based on the question I got the mass as 2.92 and the thrust as 33.4. 33.4 to match the exponent for both numbers. The answer I got when F/m=a is 33.4kg by m/s^2/2.92Kg=11.4m/s^2m/s^2. This is obviously wrong. What am I doing wrong?