Row Row Row your Boat - At which maximum speed?
The maximum speed of a rower boat is a classic example of the beauty of dimensional analysis. It was originally derived by McMahon (1971). Here it is brought again for the convenience of the Internet...
View ArticleThe Transit of Venus
The transit of Venus, June 8, 2004. Photograph taken from Jerusalem by the author, using a 10x50 viewfinder having a 90° prism. The image passing the prism is projected onto a white piece of paper...
View ArticleSnow at above freezing temperatures
Did you ever wonder how can it snow at above freezing temperatures? Well, the naive explanation is that it simply takes time for the snowflakes to melt once they penetrate above freezing air, as they...
View ArticleSnow probability calculator
Based on the analysis of whether falling snow will melt as it descends, it is possible to estimate the probability with which falling precipitation will be snow. The calculator calculates the melting...
View ArticleExhale Condensation Calculator
If the temperature is low enough or the humidity high, you can observe condensation (i.e., "fog") forming in your exhaled breath. This calculator estimates whether your exhaled breath will condense,...
View ArticleHave you heard of the silent Earthquake?
Blog topic: general physicsThe other day, I heard a very interesting talk by Prof. Fineberg (from my physics department) about dry friction, and in particular, how the contact surface between two...
View ArticleEstimating Stellar Parameters from Energy Equipartition
Many physical systems have a tendency to equilibrate the energy between different components. Sometimes it is exact, and sometimes not. This can arise from a plethora of different reasons, such as...
View ArticleStanding on ice - When is it possible?
Ice covering Grenadier Lake, High Park Toronto. The ice was 8 cm thick, enough to stand on. The small patch in the ice is a dead fish, frozen into the ice. How cold should it be and for how long to...
View ArticleParhelic Circles, Ice Haloes and Sun dogs over Jerusalem
Blog topic: general physics, general science, weather & climateA few weeks ago, a few students observed a nice phenomenon in the sky (like many others in the Jerusalem area). Knowing I liked this...
View ArticleA Nice Black Hole Merger Simulation
Blog topic: astronomy, general physics, general scienceI recently stumbled upon a nice black hole merger simulation which describes recent numerical results describing the in-spiraling and merging of...
View ArticleCorpuscular Rays in St. Peter's Basilica (the Vatican)
Blog topic: general physics A few days ago, I stayed in the Vatican (more about this one day symposium in another post). During the stay, I naturally visited St. Peter's Basilica.Near Bernini's altar...
View ArticleBush in a quantum entangled state
Blog topic: general physics, politics Nope, it isn't a science driven blog entry (though given that it is a science blog, I will include one calculation for fun and even an analogy to quantum...
View ArticleA visit to Stromboli
Blog topic: general physics, general science It seems that every time I write a blog entry I have to apologize that I don't do so more often. Apparently I don't like to admit that I am a busy person...
View ArticleFrom Masada to the Messinian Salinity Crisis
Blog topic: general physics, general science, weather & climateAnyone who has been reading my blog has noticed that I like to complain that I am too busy. Well, since my last post, I have found...
View ArticleWhy don't I believe the that neutrinos travel faster than the speed of light?
Blog topic: general physics, general scienceThree weeks ago I visited the underground laboratory of Gran Sasso near l'Aquila. Little did I know that it would make headline news so soon, for...
View ArticleEstimating the Size of the Hydrogen Atom (i.e., Bohr's Radius) using...
Peering into the hydrogen atom. The standard way to obtain the size of the hydrogen atom, also known as Bohr's radius, is to solve Schrödinger equation for the hydrogen atom. This is a somewhat...
View ArticleCharacteristics of an LC circuit using Equipartition
An LC circuit is one which has a capacitor and an inductor connected to each other. It exhibits oscillations just like a mass on a spring (a harmonic oscillator). In fact, the analogy is quite accurate...
View ArticleDust Dendrites
Blog topic: general physics, general scienceMy wife and I had our kitchen renovated. Since this involved breaking a few walls (and cutting out a new window), we knew it would raise a lot of dust. Mind...
View ArticlePredicting a supernova precursor (on SN2010mc)
Blog topic: astronomy, general physics, general scienceA very interesting paper recently appeared in nature. It describes the detection of a precursor eruption of a supernova progenitor more than a...
View ArticleEstimating the Dipole Radiation Power using Dimensional Analysis
An electric dipole is characterized by the dipole moment $d$ which depends on both the charge $e$ and a the separation $s$ (but not independently on each). Estimating the power radiated by an...
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