X2

X2 consists of small notes on facts, culture, and history of physics in Persian. The texts are in the pdf format. To view them, Adobe (Acrobat) reader 5 or later is needed. Adobe reader can be obtained from Adobe reader download.

Using, printing, and publishing these texts for non-commercial purposes is free, provided they are not altered in any sense (including text, style, and orthography). For any other use, author's permission is needed.



X2 (2017)                                        back to mamwad
X2-126 (2017/08/24) pdf If the Milky Way had a quasar

X2-125 (2017/07/28) pdf Eternal sunset

X2-124 (2017/05/29) pdf The age of the universe, and the catastrophe of 
                        the estimation of the cosmological constant

X2-123 (2017/04/17) pdf The power and the life time of a white dwarf

X2-122 (2017/02/27) pdf Wheat as food

X2-121 (2017/01/28) pdf Pluto's surface temperature


X2 (2016)                                        back to mamwad
X2-120 (2016/11/30) pdf If the arctic ice melts

X2-119 (2016/10/31) pdf If the moon becomes attached to the earth, what would be the length of the day?

X2-118 (2016/08/27) pdf How much air is needed to survive?

X2-117 (2016/07/29) pdf Cooling, using evaporation

X2-116 (2016/05/30) pdf The compact object in the center of the Milky Way

X2-115 (2016/04/29) pdf The speed of water waves

X2-114 (2016/02/28) pdf The gravitational potential energy of a mountain

X2-113 (2016/01/29) pdf Archimedes and moving the earth


X2 (2015)                                        back to mamwad
X2-112 (2015/11/30) pdf Energetic cosmic particles

X2-111 (2015/10/30) pdf Quantum mechanics and Iran, III: relativistic quantum mechanics

X2-110 (2015/08/29) pdf Internal heating of planets

X2-109 (2015/07/30) pdf The habitable zone, and the evolution of the sun

X2-108 (2015/05/29) pdf Remaining young in the gravitational field

X2-107 (2015/04/30) pdf The impulse, force, and pressure due to the rain

X2-106 (2015/02/24) pdf The water in the clouds

X2-105 (2015/01/26) pdf The minimum of the melting temperature of ice


X2 (2014)                                        back to mamwad
X2-104 (2014/11/28) pdf Revolution of the sun around the galactic center

X2-103 (2014/10/30) pdf Melting of ice, and convection

X2-102 (2014/08/25) pdf Freezing water, and cracking vessel

X2-101 (2014/07/26) pdf Perspiration

X2-100 (2014/05/30) pdf Buoyancy of the human body

X2-099 (2014/04/26) pdf The density of the rocky planets

X2-098 (2014/02/22) pdf Reducing the time needed to cook an egg

X2-097 (2014/01/31) pdf Evaporating water, raising water


X2 (2013)                                        back to mamwad
X2-096 (2013/11/29) pdf Change of the carbon dioxide ratio in the atomsphere

X2-095 (2013/10/30) pdf Which is hotter, boiling water or water vapor?

X2-094 (2013/08/31) pdf Constant angular velocity in Keplerian orbits

X2-093 (2013/07/30) pdf Quantum mechanics and Iran, II: modern quantum mechanics

X2-092 (2013/05/30) pdf The intensity and the effective intensity of the sunlight

X2-091 (2013/04/29) pdf The volume difference of liquid and gas, and the latent heat of vaporization

X2-090 (2013/02/28) pdf The laser reflected from the lunar surface

X2-089 (2013/01/30) pdf Time needed to cook an ostrich egg


X2 (2012)                                        back to mamwad
X2-088 (2012/11/29) pdf Planck mass

X2-087 (2012/10/30) pdf The boling point of the mixture of two immiscible fluids

X2-086 (2012/08/31) pdf Apparent diameters of heavenly bodies

X2-085 (2012/07/31) pdf The electric charge does not depend on the velocity

X2-084 (2012/05/30) pdf The uncertainty, and an old model of the nucleus

X2-083 (2012/04/27) pdf Ultrasonic humidifiers

X2-082 (2012/02/29) pdf A supernova as luminous as the full moon

X2-081 (2012/01/28) pdf Cooling of the erarh, and age of the earth


X2 (2011)                                        back to mamwad
X2-080 (2011/11/30) pdf Thin tubes and fluid current

X2-079 (2011/10/30) pdf Multipole radiation and the life of excited electron states

X2-078 (2011/08/10) pdf Escaping the increasing power of the sun

X2-077 (2011/07/29) pdf The focal length of thin lenses

X2-076 (2011/05/30) pdf Scattering of the sunlight in the earth's atmosphere

X2-075 (2011/04/30) pdf The angle of the rainbow

X2-074 (2011/02/25) pdf Threshold of vision

X2-073 (2011/01/27) pdf The smooth surface of a neutron star


X2 (2010)                                        back to mamwad
X2-072 (2010/11/26) pdf Magnetar

X2-071 (2010/10/30) pdf Motion with a fixed speed, in a fixed direction relative to the north

X2-070 (2010/08/28) pdf The collision which created the moon

X2-069 (2010/07/28) pdf The magnetic force felt by nonmagnetic materials

X2-068 (2010/05/28) pdf The fastest and slowest living creatures

X2-067 (2010/04/30) pdf Quantum mechanics and Iran, I: old quantum mechanics

X2-066 (2010/02/27) pdf Turning off LEDs to save electricity?

X2-065 (2010/01/29) pdf Melting temperature versus pressure


X2 (2009)                                        back to mamwad
X2-064 (2009/11/28) pdf Rotation of stars

X2-063 (2009/10/29) pdf The speed of propagation of the electric field, and the speed of charges

X2-062 (2009/08/27) pdf Maximum of the speed in running

X2-061 (2009/07/30) pdf Sharpness of phase transition

X2-060 (2009/05/30) pdf Escaping the gravitational field

X2-059 (2009/04/24) pdf Relativity and Iran

X2-058 (2009/02/27) pdf Energy released in an earthquake

X2-057 (2009/01/22) pdf Tunneling probability for electron and proton


X2 (2008)                                        back to mamwad
X2-056 (2008/11/30) pdf Adiabatic, isothermal, and evanescent sound

X2-055 (2008/10/31) pdf Surface tension in the nucleus

X2-054 (2008/08/29) pdf Thermodynamics and Iran, III: 
                        Statistical mechanics

X2-053 (2008/07/28) pdf Moon's halo, and water droplets

X2-052 (2008/05/31) pdf The electric field of the earth

X2-051 (2008/04/29) pdf The energy of rain

X2-050 (2008/02/29) pdf Are green leaves optimum for photosynthesis?

X2-049 (2008/01/31) pdf Density of elements


X2 (2007)                                        back to mamwad
X2-048 (2007/11/09) pdf Energy saving: turning off a lamp, 
                        or changing it

X2-047 (2007/10/13) pdf Energy released in the collision of 
                        a heavenly body with the earth

X2-046 (2007/08/10) pdf Thermodynamics and Iran, II: 
                        Clausius and Kelvin

X2-045 (2007/07/11) pdf Development and the price of goods

X2-044 (2007/05/31) pdf Multi-question quiz

X2-043 (2007/04/29) pdf Changing scales versus time

X2-042 (2007/02/28) pdf Sound and the amplitude of the 
                        displacement of the air molecules

X2-041 (2007/01/19) pdf Are all chemical reactions incomplete?


X2 (2006)                                        back to mamwad
X2-040 (2006/11/24) pdf Desalination of water: 
                        reverse osmosis versus distillation

X2-039 (2006/10/12) pdf Power consumption in the world, 
                        and the water of the oceans

X2-038 (2006/08/04) pdf Thermodynamics and Iran, I: 
                        Rumford, Carnot, and Joule

X2-037 (2006/07/06) pdf Old cars and fuel consumption

X2-036 (2006/05/19) pdf The magnetic fields of planets and stars

X2-035 (2006/04/02) pdf Windows and energy consumption

X2-034 (2006/02/24) pdf Elecetromagnetics and Iran, III: 
                        electrodynamics

X2-033 (2006/01/06) pdf Why there are no very-large animals
                        on the earth?


X2 (2005)                                        back to mamwad
X2-032 (2005/11/25) pdf The nucleons and the photons of the universe

X2-031 (2005/10/07) pdf The eye, the photographic film, 
                        and the digital camera

X2-030 (2005/08/31) pdf Swimming in heavy water

X2-029 (2005/07/27) pdf The power of the stars

X2-028 (2005/05/27) pdf Chemical energy, nuclear energy

X2-027 (2005/04/26) pdf The power a human needs to survive

X2-026 (2005/02/28) pdf Molecular distances and energies, 
                        and the bulk modulus

X2-025 (2005/01/15) pdf Elecetromagnetics and Iran, II: 
                        magnetostatics


X2 (2004)                                        back to mamwad
X2-024 (2004/11/12) pdf The tidal effect of the Moon on the Earth, 
                        and the change of the sidereal day

X2-023 (2004/10/15) pdf Water wasted due to faulty faucets in Tehran

X2-022 (2004/08/25) pdf Complexity of the living organisms and galaxies

X2-021 (2004/07/31) pdf Solar energy, and the world's energy consumption

X2-020 (2004/05/08) pdf Elecetromagnetics and Iran, I: 
                        the electrostatics of Coulomb and Poisson

X2-019 (2004/04/10) pdf Density of the universe at different scales

X2-018 (2004/02/14) pdf The carbon dioxide emmited by human into the atmosphere

X2-017 (2004/01/12) pdf Global warming, and the rise of ocean levels


X2 (2003)                                        back to mamwad
X2-016 (2003/12/13) pdf Galileo and the Leaning Tower of Pisa

X2-015 (2003/10/31) pdf The number of the nucleons of the observable universe

X2-014 (2003/09/24) pdf The gravitational radiation

X2-013 (2003/07/28) pdf The surface tension, and the latent heat of evaporation

X2-012 (2003/06/20) pdf The resolving power of the eye, and the heavenly bodies

X2-011 (2003/04/29) pdf Birth of the new science and Iran, III: 
                        from Lagrange to Hamilton

X2-010 (2003/03/21) pdf Cloud, rain, hailstone

X2-009 (2003/01/31) pdf The nearest neighbor of the Earth (after the Moon)


X2 (2002)                                        back to mamwad
X2-008 (2002/12/25) pdf Birth of the new science and Iran, II: 
                        Newton

X2-007 (2002/10/22) pdf Birth of the new science and Iran, I: 
                        from Kopernik to Galileo

X2-006 (2002/08/06) pdf The history of the oblateness of the earth

X2-005 (2002/07/14) pdf The lightning

X2-004 (2002/05/20) pdf Birth of the matrix mechanics in the second half of 1925

X2-003 (2002/04/09) pdf Heisenberg, Born, and Pauli

X2-002 (2002/02/22) pdf Power consumption per capita, and production per capita

X2-001 (2002/01/06) pdf The industrial revolution in terms of the spinning machine