Lightning Mate is right.
Lift is defined as a force.
However, formally, 'g' is referred to as the "acceleration due to gravity" to avoid this kind of argument.
The force on a mass caused by the acceleration due to gravity is, formally, weight.
The forces on an aircraft are in balance in straight, UNACCELERATED flight, which fits a constant rate of climb or descent as well as straight and level.
I haven't seen anyone correctly use momentum yet.
If you want a clear physical explanation of any of this, please PM me. I do this for a living.
Now, can we get back to interesting stuff like victory roll trimming and LL jokes?
F3WMB
MRAeS, MInstP