Which statement describes a disadvantage of using natural gas as an energy source? It is expensive to use. It is hard to stop using. It is a renewable resource. It is scarce in some parts of the world.

Which of the following describe possible scenarios? a) an object has zero instantaneous velocity and non-zero acceleration. b) an object has negative acceleration and is speeding up. c) an object has positive acceleration and constant velocity. d) an object has positive velocity and zero acceleration. e) an object has increasing positive position and negative velocity. f) an object has decreasing positive position and negative acceleration.