Weight on a rocket accelerating upward

[Hisui]

Homework Statement

"During the launch, a rocket is accelerated with 20.0m/s^2 upward. A 105.0kg astronaut is more concerned about his weight than about his safety and is standing on a scale. What is the scale reading in kg?"

Homework Equations

F=ma and also 4.45N=1lb

The Attempt at a Solution

So, first I solved F=ma with the information given to get 2100N, and since I don't think that N can convert to kg with an equation, I took from the front of the book that 1kg=2.20lbs where g=9.80m/s^2, so I thought that I could figure out what 1kg was with an acceleration of 20m/s^2, and I got that 4.5lbs would equal 1kg.

I then took my previous answer of 2100N and converted it to 471.9lbs and divided by 4.51lbs, hoping to get the correct kg with the acceleration given, but I got 104.6 which seems very wrong (first, because it's almost exactly the starting weight and second, because it should be higher, not lower than the starting weight). Thoughts?

 

[MrXow]

If his scale was calibrated on the Earth's surface, so that 1kg =2.2lbs, using just F=ma would yield you the correct answer.
On Earth he feels a weight of mg (105*9.8) of 1029N
When accelerating he feels a weight of ma (105*20) of 2100N
Find the ratio and multiply by his mass.

 

[Hisui]

Oh, yeah I guess I was over-thinking it. Thanks!

 

[MrXow]

No problem