Pick the best description of energy efficiency.
a. efficiency is equal to the ratio of energy you put in to the energy you get out.
b. efficiency is equal to the ratio of energy you get out to the energy you put in.
c. efficiency is equal to the sum of the energy you put in to the energy you get out.

The most important difference between a wedge and an inclined plane is a. their size b. their shape c. how they are used d. what they are made of

Why does lightning travel from clouds to the ground?

The air in an automobile tire with a volume of 2.60 ft3 is at 70°f and 21 psig. determine the amount of air that must be added to raise the pressure to the recommended value of 30 psig. assume the atmospheric pressure to be 14.6 psia and the temperature and the volume to remain constant. the gas constant of air is ru = 53.34ft⋅lbflbm⋅r(1 psia144 lbf/ft2) = 0.3704 psia⋅ft3lbm⋅r the amount of air that must be added to raise the pressure is lbm