As every engineer knows, energy calculation is straightforward. The unit of electrical energy is the kilowatt-hour (kWh), found by multiplying the power use (in kilowatts, kW) by the number of hours during which the power is consumed. Multiply that value by the cost per kWh, and you have the total energy cost.

Higher objects (with further to fall) have greater potential energy. The heaviest of 2 objects at the same height has the greatest gravitational potential energy.

By the parallel axis theorem, a pendulum that rotates around a point P and a distance l from it’s center, has kinetic energy Ekin=ω22(2mR25+ml2). Where R is the radius of the spherical pendulum bop (we assume the string or what not to be massless).

How to calculate my energy consumption

1. Device Wattage (watts) x Hours Used Per Day = Watt-hours (Wh) per Day.
2. Device Usage (Wh) / 1000 (Wh/kWh) = Device Usage in kWh.
3. Daily Usage (kWh) x 30 (Days) = Approximate Monthly Usage (kWh/Month)

useful output energy refers to the useful energy that is transferred by the device (eg thermal energy by a heater) input energy refers to the total energy supplied to a device.

Energy cannot be made or destroyed. When energy is transformed or transferred only part of it can be usefully transformed or transferred. The energy that is not used in this process is wasted energy. For example lighting a light bulb uses electrical energy to make light energy which is useful.

The U.S. has an energy efficiency of 42 percent, which means 58 percent of all the energy we produce is wasted!

The energy transfer to light energy is the useful transfer. The rest is ‘wasted’. It is eventually transferred to the surroundings, making them warmer. This ‘wasted’ energy eventually becomes so spread out that it becomes very difficult to do anything useful with it.