Ok dokey to put this in simple straight forward language let's ask what determines an aircraft's ability to climb (for a sustained time period not for a few seconds by just pulling up the nose/dumping flaps)? In a nutshell climb is dependent upon having more power available than is required to maintain level flight in a given configuration. This is why multi-engine aircraft can loose most or even all of their ability to climb after an engine failure.
Also, let's not forget the difference between weight and mass. Mass is an object's resistance to acceleration. Weight is a the product of mass and the acceleration of gravity. The pound is a unit of force that equals a mass of one slug acted on by the local constant of gravity expressed in feet/second/second...32ft/sec^2 is a common value.
Hope this helps!
Jon
