b_jonas

190 reputation

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visits	member for	1 year
	seen	May 16 at 8:53
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	190 reputation	bio	website		visits	member for	1 year
7 badges		location			seen	May 16 at 8:53

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May 16	comment	Superluminal particles with causality See also the usenet physics faq, question "Do tachyons exist?": math.ucr.edu/home/baez/physics/ParticleAndNuclear/tachyons.html
May 14	comment	Why metric system uses kilogram as a basic SI unit? @Gugg: you can distinguish because many derived units such as newton, joule, pascal, volt etc are products of kilogram and other basic units. Because of this, when you do calculations writing all numbers in SI measurements, you use kilogram so it matches values with other units, and to match expectations of other people. The gram only behaves like a basic unit when you write values with prefixed units and the unit starts with kilogram.
May 5	awarded	Citizen Patrol
Apr 30	awarded	Critic
Mar 12	comment	Seeing a mirage through mirror? Vampires don't have a reflection in mirrors, right?
Mar 12	awarded	Commentator
Mar 12	comment	How much energy would it take to blow up the earth? qntm.org/data gives the same figure.
Feb 27	comment	Speed of an object in air versus in vacuum Firework rockets have a solid propellant and use the oxygen from the air, so they don't work in vacuum.
Jan 19	accepted	Can you tell just from its gravity whether the Moon is above or below you?
Jan 18	comment	The direction of the Lorentz Force Is the green area on the left hand side the north magnetic pole? I can't make out the letter on the figure.
Jan 11	awarded	Nice Question
Jan 11	awarded	Scholar
Jan 11	accepted	How can the Moon have such a strong effect on the ocean?
Jan 11	comment	How can the Moon have such a strong effect on the ocean? Oh! This also explains why the difference between the polar and equatorial radius of Earth is about 3•10^(-3) times the radius, as the rotation of Earth contributes about 3•10^(-3) times the gravitational acceleration on the Equator surface.
Jan 11	asked	How can the Moon have such a strong effect on the ocean?
Jan 10	awarded	Student
Jan 10	asked	Can you tell just from its gravity whether the Moon is above or below you?
Dec 27	comment	How does electron capture occurs? Just to clarify, there's also a proton from the old nucleus involved that ceases to exist in the reaction, right?
Dec 6	comment	Does a wing in a potential flow have lift? Nice! So that's the answer to xkcd.com/803 (Airfoil).
Oct 28	comment	How do I find the initial velocity in this problem? I thought the electrons would be ejected from a cathode in the X-ray machine so they have essentially zero speed.