The answer would be energy, because all wave emitters give off at least one type of energy....
Eating. Your muscles in your arms and mouth use energy to feed itself. Then your body digest the food which also takes energy.
Sleep. When your tired, you don’t have much energy. It is said that you use more energy while your sleeping. But how do you become energized if you were using even more energy than before?
(a) The value of the gravitational acceleration is given by:
where
is the gravitational constant
M is the Earth's mass
is the Earth's radius at the pole
If we use the value for g given by the problem, 
, and we rearrange the equation above, we find the value of the Earth's mass:
(b) The value we found for the Earth's mass is 
, and we see that this value is slightly larger than the accepted value of 
.
