We all think we know what a force is. We can sense force, but what is it?
We believe that all forces come from the properties of electric and magnetic fields. They are found in their purest form inside a television tube.
A well insulated stout wire runs to the side of the tube. DO NOT TOUCH it. It is connected to the inside of the screen and the end of the electron gun. Depending on the size of the television it could carry between 2,000 and 20,000 volts. This voltage acts within the electron gun to exert a force on the electrons and accelerate them into a beam.
Around the neck of the tube are four coils of wire, a horizontal pair and a vertical pair. These generate the magnetic fields which bend the electron beam so that it scans back and forth across the screen drawing a picture from top to bottom 50 or 60 times a second.
There is also another force which acts on every atom and every electron giving the television weight, but it is millions of billions of billions of billions of billions times smaller. It just seems big because there is a tiny force on each of thousands of billions of billion of electrons and atoms and they all add up make the weight of the television.
We believe that force is the process by which energy is transferred between electric fields and magnetic fields.
The voltage in the electron gun creates an excess of electrons at the back end (cathode) and a deficit at the end near the screen (anode). For each missing electron, there is a net positive charge attracting the electrons on the cathode. The cathode is heated allowing electrons to escape. Once free, they are acted upon by the forces from each of the excess electrons on the cathode and each of the atoms at the anode which are missing an electron.
If we could look at just one pair of an electron and an atom with a missing electron, we would see that both the electron and the atom have electric fields. We say that each possessed a kind of energy by virtue of its position in the other's electric field. This potential energy wants to escape and it can do this if the electron moves closer to the atom. We say it exerts a force which accelerates the electron. Moving electrons are surrounded by magnetic fields. As the electron accelerates, the change in its speed causes the amount of energy in its magnetic field to change. The potential energy of the electric fields is changed into kinetic energy stored in the magnetic field surrounding the electron.
Every electron and every quark has its own electric field and they all coexist in space together. There is a very, very, very small effect which they have on each other reducing the amount of energy they have stored in them. This very, very, very small effect gives us the force of gravity.
Physicists are taught that there are two other kinds of force which are involved in nuclear physics. The strong force holds protons and neutrons together and the weak force sometimes upsets the equilibrium causing nuclei to break up in what we call radioactive decay.
We believe that the strong force is a manifestation of the magnetic force between magnets. We believe that radioactive decay can be explained without the invention of the weak force.
One concept of Newtonian physics is that every force has an equal and opposite force. We say that the force accelerating the electron is balanced by the inertial force with which the electron resists acceleration. There are two types of inertial force, one which resists acceleration in the direction of motion, the other which resists a change in direction is called centrifugal force.