Chapter 1

Figures from Halliday, Resnick, Walker, “Fundamentals of Physics” 9 th edition as noted.

Additional slides from Thorton & Rex, Modern Physics, 3 rd ed slides, prepared by Anthony Pitucco, Ph.D., Pima Community College

Book website Other websites

~400 BC Philosophy

EVOLUTION

Natural Philosophy & Science (study of) ~1600 ~1634 ~1687 ~ 1834 ~1890 ~1930 Natural Science (knowledge based) (first ‘scientists’ appear) Classical Physics Physics & Chemistry become separate fields Modern Physics (emergence of relativity & quantum theory)

MECHANICS CLASSICAL PHYSICS 1.1

ELECTRICITY AND MAGNETISM THERMODYNAMICS CONSERVATION LAWS

Classical Physics

CONSERVATION LAWS Energy, Linear Momentum, Angular Momentum, Charge

• Mechanics – – – – Galilieo Newton Kepler Hook – – Kepler … • – – – – – Electromagnetism – – – – Coulomb Oersted Young Ampere Faraday Henry Maxwell Hertz … • Thermodynamics – – – – Thompson Carnot Joule Clausius – – Kelvin …

Conservation Laws

• • • •

Conservation of energy:

– The total sum of energy (in all its forms) is conserved in all interactions.

Conservation of linear momentum:

– In the absence of external forces, linear momentum is conserved in all interactions.

Conservation of angular momentum:

– In the absence of external torque, angular momentum is conserved in all interactions.

Conservation of charge:

– Electric charge is conserved in all interactions.

Mechanics

Three laws describing the relationship between mass and acceleration.

 Newton’s first law (law of inertia): An object in motion with a constant velocity will continue in motion unless acted upon by some net external force.

 Newton’s second law: Introduces force (F) as responsible for the the change in linear momentum (p):   Newton’s third law (law of action and reaction): The force exerted by body 1 on body 2 is equal in magnitude and opposite in direction to the force that body 2 exerts on body 1.

Electromagnetism

• Gauss’s law (Φ

E

): (electric field) • Gauss’s law (Φ

B

): (magnetic field) • Faraday’s law: • Ampère’s law:

Thermodynamics

• First law: The change in the internal energy ΔU of a system is equal to the heat Q added to a system plus the work W done by the system ΔU = Q + W • Second law: It is not possible to convert heat completely into work without some other change taking place. • The “zeroth” law: Two systems in thermal equilibrium with a third system are in thermal equilibrium with each other. • Third law: It is not possible to achieve an absolute zero temperature

STUPID THINGS PEOPLE SAY

• •

Lord Kelvin 1900

– “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.”

Albert Michelson 1894

– “The more important fundamental laws and facts of physical science have all been discovered, and these are so firmly established that the possibility of their ever being supplanted in consequence of new discoverys is exceedingly remote…”

Some Mysteries of 1895-1915

• What are the positive and negative charges in a material and how are they arranged? (atom) JDalton’s 1808 Chemical Philosophy sketches http://en.wikipedia.org/wiki/File:Daltons_symbols.gif

• How does one explain the distribution of velocities in a gas? (Maxwell-Boltzmann)

•

Some Mysteries of 1895-1915

Why do electrons moving through a gas loose energy in increments? (Franck-Hertz) Wikipedia on Franck-Hertz • • Why do ‘alpha rays’ bounce back 180 o ? (Geiger Marsden-Rutherford) What medium do light waves travel in? (Michelson Morley)

Some Mysteries of ~1895

• Why does light kick electrons out of a surface only above a certain frequency which is different for each material? (photoelectric effect) • What is this radioactivity stuff?

Some Mysteries of ~1895

• How does one explain the perihelion precession of planet Mercury?

Wikipedia on precession of Mercury • • Why does the electron have a magnetic moment? (Stern-Gerlach) Is light a particle or a wave?

~400 BC Philosophy

EVOLUTION

Natural Philosophy & Science (study of) ~1600 ~1634 ~1687 ~ 1834 ~1890 ~1930 Natural Science (knowledge based) (first ‘scientists’ appear) Classical Physics Physics & Chemistry become separate fields Modern Physics (emergence of relativity & quantum theory)

PEOPLE OF MODERN PHYSICS 10 minute presentations *** next week ***

Historical Characters

• • • • • • • • • William Hamilton (1805-1865) David Hilbert (1862-1943) Max Planck (1858-1947) Albert Einstein (1879-1955) Niels Bohr (1885-1962) Werner Heisenberg (1901-1976) Samuel Goudsmit (1902-1978) George Uhlenbeck (1900-1988) Hendrik Lorentz (1853-1928) • • • • • • • • • • Louis de Broglie (1892-1987) Erwin Schrödinger (1887-1961) Max Born (1882-1970) Wolfgang Pauli (1900-1958) Paul Dirac (1902-1984) John von Neumann (1903-1957) Otto Stern (1888-1969) Walther Gerlach (1889-1979) Pieter Zeeman (1865-1943) Paul Ehrenfest (1880-1933)

Women People

• • • • • • • • • • • • • • • Lise Meitner 1878-1968 – Radioactivity & nuclear Gertrude Scharff Goldhaber 1911-1998 – neutrons emitted during fission Sulamith Goldhaber 1923-1965 – Kaon studies, CP violation, Time-reversal violation Noeme Benczer Koller – 2 photon transitions, Administrative structure of physics in the US Bice Sechi-Zorn – Gluon jets Katherine Way 1903-1996 – Nuclear structure databases Chien-Shiung Wu 1912-1997 – Parity violation Evans Hayward Faye Ajzenberg-Selove E. Margaret Burbidge – B 2 FH Maria Goeppert-Mayer 1906-1912 – Nuclear shell model, spin-orbit, 235U Helen Quinn 1943 – Unification of strong, weak, EM forces Rosalind Franklin 1920-1958 – X-ray crystallography of double helix Hertha Sponer 1895-1968 – Application of QM to atomic & molecular d

Men People

• • • • • • • • • • • • • • • Otto Hahn 1878-1968 Isidov Isaac Rabi 1898-1988 – Magnetic properties of nuclei Edward Teller 1908-2003 – “If you’ve got a problem, he’s got a bomb” Leo Szilard 1898-1964 – Conceived chain reaction, “scientist with a conscience” David Bohm 1917-1992 – McCarthyism, thesis work got classified before he could get a degree.

Freeman Dyson 1923 – Triga, JASON, “A-bomb kid” Eugene Wigner 1902-1995 – Symmetry groups Richard Feynman 1918-1988 – “½ genius - ½ buffoon, NO, all genius - all buffoon” Abdus Salam 1926-1996 – Elementary particles, electroweak theory Alvin Weinberg 1915-2006 – “When piles go critical in Chicago, we celebrate with wine, when piles go critical in Tennesse, we celebrate with Jack Daniels” Murray Gell-Mann 1929 – “the man with 5 brains” Eugen Merzbacher 1921 – Father sold radioactive toothpaste Larry Biedenharn 1922-1996 – Father 1 st to sell Coca-cola Enrico Fermi 1901-1954 – “Sound of Music” c

Pairs of characters

• • • • • • • • • • • Joe Weber (1919-2000) / Virginia Trimble (1942-) – Did early maser work; considered the optical maser – quantum electronics, gravity wave, gravitation,… NAVAL ACADEMY GRAD, quantum electronics, gravity wave, gravitation,… Maurice (1911- ) / Gertrude Scharff Goldhaber D D D D d Paul Dirac (1902 ) / Margit Wigner Margaret Burbidge (1919- ) / Geoffrey Burbidge (1925- ) D D

Presentation Evaluation

About Who?

Length of Presentation Amount of Research Performed Presentation Style Talk was prepared Balance of Personal vs Physics Information Interesting facets of personal info uncovered Photographs & artifacts of their life uncovered This person would be classified as a I wish I had picked this person to talk about <8 min Not Much rough last minute all physics had no life what ’ s a photograph?

storm drain no ~ 10 min Ave ave neutral reasonable balance Ave Ave brick in the wall neutral >12 min A Lot real smooth far in advance all personal movie star YouTuber party animal yes

 

t r

   

x

 

y z

 

t stationary coordinate system

Position

(x,y,z,t)

Three astronauts, propelled by jet packs, push and guide a 120 kg asteroid toward a processing dock, exerting forces F 1 = 32 N F 2 = 55 N F 3 q 1 q 2 = 41 N = 30 = 60 o o What is the asteroid’s acceleration?

Forces & Acceleration

On Aug 10, 1972, a large meteor skipped across the atmosphere above western US and western Canada, much like a stone skipped across water.

The meteorite’s mass was about 4 * 10 6 kg; it’s speed was about 15 km/s. Had it entered the atmosphere vertically; it would have hit the Earth with about the same speed.

(a) Calculate the meteorite’s kinetic energy.

(b) Express this in terms is tons of TNT. 1 ton TNT = 4.2*10 15 J.

Kinetic Energy

Photograph by James M Baker http://ngm.nationalgeographic.com/2008/08/earth-scars/stone-text http://ngm.nationalgeographic.com/2008/08/earth-scars/alvarez-photography http://www.youtube.com/watch?v=ZUyoDkp30-U

Conservation of Energy

Conservation of Energy (reading graphs)

Conservation of Energy (reading graphs)

Conservation of Energy (reading graphs)

Conservation of Energy (reading graphs)

Conservation of Energy (reading graphs)

Conservation of Momentum

HRW 9-117 A collision occurs between a 2 kg particle traveling with velocity 

v

1   4

i

ˆ  5

j

ˆ and a 4 kg particle traveling with velocity

v

 2   6

i

ˆ  2

j

ˆ

m

/

s m

/

s

After the collision, the particles stick together.

What is the final velocity?

Conservation of Momentum

Particle 1 Alpha particle m 1 = 4 amu Particle 2 Oxygen nucleus m 2 = 16 amu

v

2

f

 1 .

20  10 5 q 1 q 2  64

o

 51

o m

/

s

Find v 1

i

and v 1

f

Conservation of Angular Momentum

HRW 11-45 A man stands on a platform which is rotating at 1.2 rev/s. His arms are outstretched and he holds a brick in each hand. The total rotational inertia is 6 kg m 2 .

He brings his arms in so that the rotational inertia decreases to 2 kg m 2 .

What is his final rotational speed?

Conservation of Angular Momentum

HRW 11-46 The rotational inertia of a collapsing spinning star drops to 1/3 its initial value.

What is the ratio of the new rotational kinetic energy to the initial rotational kinetic energy?