Transcript Introduction to Mechanics

Mechanics: “Classical Mechanics”
• Classical Physics:
– Foundation of pure & applied macroscopic
physics & engineering!
– Newton’s Laws + Boltzmann’s Statistical
Mechanics (& Thermodynamics):
Describe most of macroscopic world!
– However, at high speeds (v ~ c): Need
Special Relativity. Ch. 7
– Small size (atomic & smaller): Need
Quantum Mechanics. Physics 5301!
– Classical Mechanics: 17th & 18th centuries,
but still useful today!
Mechanics
• Science of HOW objects move (behave)
under given forces.
• (Usually) Does not deal with sources of
forces. Answers the question: Given the
forces, how do objects move?
• Forces are classified into four types:
Four Fundamental Forces Of Nature!
– Mechanics applies to all four!
4 Fundamental Forces of Nature
Sources of forces: In order of decreasing strength
• Strong Nuclear Force:
– Binds nuclei together. Still being researched.
• Electromagnetic Force:
– E&M phenomena. Chemical forces. Most everyday
forces. Maxwell, Coulomb, Ampere, Faraday, ...
• Weak Nuclear Force:
– Nuclear decay. Fermi, Bethe, others. Still being
researched.
• Gravitational Force:
– Newton (classical mechanics)
– Einstein (general relativity)
4 Fundamental Forces of Nature
Sources of forces: In order of decreasing strength
4 Fundamental Forces: Sources of forces
• “Electro-Weak” Force:
– Since ~ late 1960’s, in some sense have
reduced the 4 fundamental forces to 3!
– Electromagnetic Force & Weak Nuclear
Force combined into one theory.
– S. Weinberg & A. Salaam: 1972 Nobel Prize
in Physics!
The Rest of Physics!
• What we’ve mentioned is  all of physics except:
• Statistical Mechanics: (Physics 5305)
– Mechanics of systems of huge numbers of
particles (>> ~ 1023).
– Uses probability & statistics methods to
compute macroscopic properties from
microscopic force laws between particles.
– The major LINK between microscopic &
macroscopic physics!
– Contains Thermodynamics as a sub-theory!