acceleration due to gravity

[gimblet]

Why do objects accelerate due to gravity?

[turin]

It depends on the context. If you are talking first semester physics or something like that, then the acceleration is due to the force of gravity according to Newton's law: a = F/m. If you are talking more sophisticated as in general relativity, then objects accelerate because spacetime moves past them. The surface of the Earth accelerates upwards at a rate of about 10 m/s² with respect to spacetime.