Power Formulas

The electrical unit for measuring work is called a "joule." One joule is equal to one ampere flowing for one second under the pressure of one volt. An electrical force may exist without work being done. This is the condition that exists between the terminals of a battery when no equipment is connected to them. When a piece of equipment is connected to the terminals of the battery, current will flow and work will be done. "Power" is the rate of doing that work. The mathematical formula for power can therefore be given as: power = work/time. In the same way, we can find a mathematical formula for electrical power: Electrical power = electrical work/time. A "watt" is an electrical unit of power. The watt is equal to one joule of electrical work per second, giving us the formula: Watt = joules/seconds = volts x amperes x seconds/seconds. In an automotive lighting circuit, the current is 8 amperes and the voltage is 12. Therefore, the number of watts being used is: 8 (amps) x 12 (volts) = 96 watts. The unit for measuring mechanical power is called "horsepower." In experimentation, it has been found that one horsepower is equal to 746 watts. The first car on the moon was electric, and it took ten years to design. The cost was something around sixty million dollars. It went with the Apollo 15 space crew in 1971.