1. Gravity is the force the prevents the Sun from expanding despite the fact that it is a hot gas and keeps the Earth forever falling towards the Sun in it's orbit and keeps all the people in this room in their seats. One way to look at gravity is that it is an attractive force between objects with mass.

  2. Electric Force is a force felt between charged particles like electrons (e-) and protons (p+). There are both attractive and repulsive electrical forces. Like charges repel, opposites attract. The Electrical Force holds atoms and molecules together and is useful for all kinds of nifty gadgets that have been built in the last 150 years.

    Fun note: The electric force is what keeps you from falling through the chair and floor and earth and being cooked in the center of the Earth. You are suspended above your chair by the repulsive force of the protons in your body against the protons in the chair.

  3. Nuclear Force. If you think about it for a minute, nuclei of atoms which contain protons (positively charged) and neutrons (no charge) should not be stable. All those ``like'' charged protons should be repelling one another and fly right out of the nucleus. Since nuclei ARE stable, it can be inferred that there is another force that is stronger than the electrical force which glues those nuclei together. This is the Nuclear Force or the Strong force. The Nuclear force would right now be binding EVERYTHING together except for the fact that it acts over only very tiny distances.

Nuclear Fission


There is a short string of similar reactions that go on in any hot gas of hydrogen atoms. This is called the proton-proton cycle or the P-P cycle.

Step I: tex2html_wrap_inline525

Step II: tex2html_wrap_inline527

Step III: tex2html_wrap_inline529

The whole thing can be summarized with one net reaction:



Michael Bolte
Fri Feb 6 23:24:56 PST 1998