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The 4 Fundamental Forces

The 4 Fundamental Forces. What is a force?. A push or a pull . If something is not moving, a push or pull could start it moving. If something is moving, a push or pull could stop it. YAWN!!!. If everything stayed the same, we would be BORED.

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The 4 Fundamental Forces

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  1. The 4 Fundamental Forces

  2. What is a force? • A push or a pull. • If something is not moving, a push or pull could start it moving. • If something is moving, a push or pull could stop it.

  3. YAWN!!! • If everything stayed the same, we would be BORED. • For things to change, something’s got to move. • For something to move, it needs a force.

  4. Forces vs FORCES!!!! • Lots of little forces are happening all the time: you flick away a piece of dust, you kick a soccer ball, you pull down a curtain, you stop a speeding bullet with your teeth…. • Each of these forces causes something to move or to stop moving. • These are real forces, but the universe is controlled by some FORCES that are even BIGGER.

  5. The Four Fundamental Forces • From what we know about the universe, all movements of matter (stuff) are caused by just four forces. • These forces were created during the first seconds after the Big Bang created the universe. • They make everything ‘work.’

  6. 1. Gravity • Right now, you’re being pulled down by Gravity. • We feel gravity almost all the time (not in outer space, but it is still there), but it is most obvious when stuff falls down.

  7. Aristotle’s Error • Aristotle was a brilliant philosopher who lived several thousand years ago. • He believed that heavy things fall faster than light things. • He dropped a rock and a feather, and the rock landed first. • BUT the items were not shaped the same.

  8. Drop a piece of paper and a ball at the same time. What happened? • Now crumple the paper into the same shape as the ball and drop again. • What happened?

  9. Galileo Disproves Aristotle • Galileo  • all objects fall at the same rate of speed, no matter how big or small they are. • Legend: he dropped one metal ball and one wood ball off the Leaning Tower of Pisa. They landed at the same time.

  10. To the Moon! • Astronauts tried Galileo’s experiment: • dropping a hammer and a feather. • They landed at the same time. • With no air resistance to slow down the wide, flat feather, only gravity was at work. • Galileo was right.

  11. Galileo had realized that gravity makes things fall toward the center of the Earth. • He also figured out that the Earth’s gravity holds the Moon in orbit around it. • Then he realized that the Sun has gravity, and it holds the planets in orbit around it. • Based on Galileo’s work, Isaac Newton was able to tease out the exact rules of gravity.

  12. Newton’s Laws of Gravity • All matter has gravity • Gravity pulls masses together • The more mass, the more gravity • The farther away, the less gravity

  13. GRAVITY IS A FUNDAMENTAL FORCE • Nobody knows why matter has gravity, but we do know exactly how it behaves. • Maybe the graviton? • It appears to behave the same everywhere in the Universe. • Therefore, it is a Fundamental Force.

  14. So, the next question is…. • HOW COME WE DON’T GET PULLED TO THE CENTER OF THE EARTH BY GRAVITY????

  15. 2. Electromagnetism • What familiar words make up ‘Electromagnetism?’

  16. Electro + Magnet • Positive charges are attracted to negative charges. • Like charges (+ and + or – and --) push each other apart. Fe = Ke(q1q2) / r2 This should look familiar… • Fe is the electric force between the charges • Ke is Coulomb's constant • q1 is the first charge and q2 is the second charge • r is the distance between the centers of the charges

  17. EM is in anything that has a charge • Electrons & Protons • Ions • Parts of Molecules • Electric currents • Magnets • The ink sticking to your notebook paper • The paint sticking to the wall • Car batteries

  18. EM also lets us ‘feel’ solids, liquids, and gases…. • Atoms are almost all empty space. • But they have shells of negatively-charged electrons, and those electrons in your hand repel the electrons in your pen. • The electrons in solids are close together. • Lots of them are touching the electrons in your ‘solid’ fingers. • The pen feels ‘solid.’

  19. So about that falling thing…. • We don’t get sucked to the hot molten core of the earth every time we jump up and down because EM stops you. • Those electrons are repelling each other • The ground is repelling you…

  20. EM>>Gravity • Magnets lifting cars • Magnets separating “dark” sand

  21. ELECTROMAGNETISM is a Fundamental Force • EM is a STRONGER Fundamental Force than gravity  • EM is 1037 x stronger than gravity

  22. Wait a sec…. • Inside the middle of every atom is a hunk of protons. • They all have positive charges. • If like charges (+/+ or -/-) repel each other, then how come the protons don’t explode out of the nucleus???

  23. 3. Strong Nuclear Force • The protons don’t repel each other because the Strong Nuclear Force holds them together.

  24. Strong Nuclear Force >> EM • The strong force is a Fundamental Force: • Generated by GLUONS acting on Quarks • 100x stronger than the EM force. • Only acts on the nucleus ~ 10-15 meters • Without it, there would be no atoms, no elements, nothing. • The universe would be a big cloud of bumping particles.

  25. There would be no us….

  26. 4. Weak Atomic Force • Why aren’t electrons sucked into the nucleus of the atom? • The Weak Force • Beta Emission: no p+ + e-Radioactivity • Radiometric dating • nuclear power and atom bombs

  27. The Nuclear Weak Force • Shortest range  1000 x shorter than the Strong Force • Lies within the diameter of the nucleus • Causes an instability of the nuclei • Really Weak  106 x weaker than the Strong Force • 1033 x stronger than gravity

  28. The 4 Fundamental Forces • In order of Strength • Strong • Electromagnetic • Weak • Gravity • In order of Distance • EM & Gravity • Strong 10-15 m • Weak 10-18 m

  29. So how do these 4 FORCES fit together? • The Scotsman Michael Faraday • Watched lightning storms • figured out how electricity and magnetism went together • Quantum Mechanics EM, Strong and Weak & the realm of the very Small • Interactions between Quarks, Gluons, and Leptons • But what of Gravity?

  30. Grand Unified Theory (GUT) • Einstein’s General Theory of Relativity  Gravity & the very Large • Einstein spent the remaining 30 years of his life trying to figure out how ALL the forces fit together. • He failed.

  31. String Theory • Is the closest thing we have to GUT • Higgs-Boson Particle

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