Speed of Light

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Speed of Light
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Speed of Light

• What is the fastest speed which anything can move?

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Speed of Light

• What is the fastest speed which anything can
  move?
• In a vacuum nothing travels faster than the speed
  of light.

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Speed of Light

• Does the speed of light change for observers
  depending on their position or motion?

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Speed of Light

• Does the speed of light change for observers
  depending on their position or motion?
• The speed of light is the same for all observers
  no matter how they or the light source are moving.

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NaturesFour Fundamental Forces
STRONG
Electromagnetic
Gravity
weak
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The four forces found in nature, listed from
strongest to weakest are

• The Strong Nuclear Force
• The Electromagnetic Force
• The Weak Nuclear Force
• Gravity

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Strong Nuclear Force

• The strongest of the four forces.
• Acts inside the nucleus.
• Attractive force between protons and neutrons
  that holds the nuclei of atoms together.
• Very short range force.gt Acts over a distance of
  10-15 m which is the diameter of a medium size
  nucleus.

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Electromagnetic Force

• 2nd strongest force.
• Strong force is 137 times stronger.
• The electromagnetic force holds atoms and
  molecules together.
• Responsible for all forces experienced with the
  exception of gravity. (All contact forces are
  electromagnetic in nature).
• Range is infinite (strength obeys inverse square
  law.)

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Weak Nuclear Force

• 3rd strongest force.
• Strong force is 1,000,000 times stronger.
• Responsible for radioactive decay and neutrino
  interactions.
• VERY short range force. gt Acts over a distance
  of 10-18 m which is 0.1 of the diameter of a
  proton.

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Gravity

• Weakest of the four forces. Strong force is1.67 x
  1038 times stronger.
• Responsible for the structure of the universe on
  the larger scale.
• Range is infinite (strength obeys inverse square
  law.)

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RecapThe four fundamental forces

• STRONG Glues protons together, protons must be
  very close, strongest of all forces, limited
  range
• WEAK responsible for radioactive decay
• neutron decay
• ELECTROMAGNETIC electrons kept in orbit.
  Opposites attract holds atom together
• GRAVITY the weakest of the forces four
  fundamental forces, yet it, all objects are
  influenced by it, at an infinite distance