# Work-Energy and VRI

The Work/Energy is an interesting one. Losely define, energy is ability to do work. Much like changing Potential Energy to Kinetic Energy and vice versa.

This picture from www.physics.upenn.edu describes what work is done with the gravitational force. Most people knows W=Fxd. W is work, F is force (gravitational) and d is distance. Applying force on a mass over a distance accounts for the work done.

If F is analogy of V (voltage) which pushes or pulls the electrons to move over a distance for a period of time, the electrons experience the resistance much like the mass needs to overcome the friction to move over that distance.

The analogy is that mass is moving at constant speed and electrons are also moving at constant speed. One is moving under gravitational force, and electrons are moving under an electric potential, voltage or battery. The friction experiences by the mass is the similar to the resistance experiences by the electrons.

W=Fd for the mass and W=Pt for electric circuit and since P=VI, then W=(E/Q)x(Q/t)xt=E, meaning E, energy per charge (volt) equals to W, work done (joules) by a charge.

If the mass moves a further distance, more work is done. If the electron moves a further distance in the circuit or over a longer period of time, more work is done.

The above picture is from http://www.petervaldivia.com.

Do not think about a mass is a single electron but a mass of electrons. Think about the force (gravitational) is force per unit mass which is similar to the voltage (battery). Voltage is also called electromotive force which is the electromotive force on a unit charge (electron). Actually Voltage V is defined as Energy per unit charge. It is not difficult to tell that Energy is related to Force as in the equation W=Fd and E=W.