Why have to push beverage cart fwd during climb?
AtomKraft,
The reason that the cabin crew has to push the beverage carts when moving forward during a climb is that the thrust is up, not because of pitch attitude. With thrust set for climb, the force needed to push the carts up the aisle would the same whether climbing at the flight path angle that maintains constant speed (i.e., the normal climb condition), flying level with increasing airspeed, or at some extremely high pitch attitude with airspeed decreasing.
The bottom line is that gravity acts on the airplane and its contents equally so it does not generate forces between the two. In the air, only thrust and aerodynamics generate forces that are sensed by the contents and occupants of the airplane.
One other thing to ponder - if pitch and roll attitude were to determine forces felt within an airplane, how would it be possible to perform a barrel roll with continuous positive acceleration along the body Z-axis?