Solar energy and Geothermal energy are your answers :)
a substance's density is the same at a certain pressure and temperature, and the density of one substance is usually different than another substance.
Voltage = current(I) * resistance (R)
V = 18
R = 6
18 = I * 6
I = 18/6 = 3 Amps or D
Actually, the speed of the earth is the same everywhere, taking the angular speed as the valid measure of the speed
