301/ Astro Fall 2006 (50405) Introduction to Astronomy
http://www.as.utexas.edu/~sj/a301-fa06
Instructor: Professor Shardha Jogee TAs: Biqing For, Candace Gray, Irina Marinova
Lecture 11: Tu Oct 10
North Korean nuclear test on Mon Oct 9 2006
North Korea claims to have conducted nuclear test on an atomic fission bomb on Oct 9,2006 See todays lecture on energy released by nuclear fission
Recent and Upcoming topics in class
Energy -- Energy and Luminosity -- Forms of Energy. -- Principle of Conservation of Energy -- Equivalence of Mass and Energy or E=mc2 -- What fraction f of the stored energy do different processes
Chemical reactions Nuclear fusion Nuclear Fission Accretion of matter onto a black hole
-- Atomic Nuclear Fission Bomb dropped on Hiroshima and Nagasaki North Korean nuclear test on October 9, 2006 -- How much energy is released during nuclear fusion ? The missing mass problem
Energy and Work
Forms of Energy
See in-class notes Radiative energy (light) Sound energy Kinetic energy Thermal Energy
Temperature affect the motion of atoms
A macroscopic body (e.g, a hot kettle, a star, your hand) contains atoms that are moving randomly
The temperature of a body determines the random speed at which its atoms move High temperature high speed large thermal energy Low temperature low speed low thermal energy
Thermal Energy
Thermal Energy of each particle depends on temperature T Total thermal energy of 2 blocks of matter having same volume is larger for block having more particles higher density
The Kelvin, Celsius and Fareneit temperature scales
Celsius temperature = Kelvin temperature - 273 Celsius temperature = (Farenheit temperature - 32) /1.8
K 0 273 373 1800 3000 5800
Example Absolute zero Water freezes Water boils Iron melts Iron vaporizes Suns surface
Speed of Atoms Atoms at rest 500 meters/sec
7 km/sec
What fraction f of the stored energy do different processes extract?
Einsteins equivalence principle Energy stored in Mass M is given by E= Mc2 1) Chemical reactions extract energy E = f Mc2 where f = 10-9 2) Nuclear fission of Uranium or Plu extract energy E = f Mc2 where f < 10-3
Uranium bomb on Hiroshima, Plutonium bomb on Nagasaki
3) Nuclear fusion of a mass M of H into He extract energy E = f Mc2 where f = 0.007
Hydrogen bomb in 1952
4) Infall of mass M on the disk accretion of a black hole releases E = f Mc2 where f = 0.1
Atomic nuclear fission bomb dropped on Hiroshima
Nuclear fission of Uranium or Plu extract energy E = f Mc2 where f < 10-3
Aug 6, 1945: Hiroshima hit by an atomic fission bomb made of Uranium. Mass of Uranium was a few kg of which 1 g was entirely converted to energy Energy released equivalent to detonating 15,000 tons (33 million pounds) of TNT
Atomic Nuclear Fission Bomb dropped on Nagasaki
The atomic bomb mushroom cloud seen from an American aircraft
The atomic bomb mushroom cloud over Nagasaki on August 9, 1945
Atomic Fission Bomb: Nagasaki
Nagasaki 2 days before the atomic bombing
Nagasaki 3 days after the atomic bombing
Atomic Fission Bomb: Nagasaki
DAMAGE CAUSED BY THE ATOMIC BOMB EXPLOSION
* Levelled Area...................6.7 million square meters * Damaged Houses: Completely Burned ------11,574 Completely Destroyed-----1,326 Badly Damaged------------5,509 Total-------------------18,409 * Casualties Killed------73,884 Injured-----74,909 Total------148,793
(Large numbers of people died in the following years from the effects of radioactive poisoning.)
North Korean nuclear test on Mon Oct 9 2006
North Korea claims to have conducted nuclear test on an atomic fission bomb on Oct 9,2006 Energy released is thought to be equivalent to detonating 550 tons of TNT
1. Energy released during nuclear fus...