As a rocket ascends, its acceleration increases even though the net force on it stays constant. Why?

As a rocket ascends, its acceleration increases even though the net force on it stays constant. Why? (Assume a traveling distance small enough that the thrust, acceleration due to gravity and atmosphere do not change.)

There is a mass decrease as fuel gets consumed. Acceleration is increased as a result of the samenet force acting on a smaller mass.It does have to do with Newton's Second Law:F_net = maa =...