mwengler
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 Jan 25 comment What happens to wheels of a car moving near speed of light? This is not a duplicate of the rotating bar problem. Here we have a relativistic rotation, AND a relativistic translation. It is much more similar to Gamow's cyclist spacetimetravel.org/tompkins/node7.html a bicycle moving at 0.93 c. The link covers nicely what happens to the wheels, or rather that the wheels must actually be assembled while they are rotating because the circumference of the spinning wheel is much higher than that of the stationary wheel. What happens to the wheel is also very involved in the Ehrenfest paradox, look it up. Jul 18 awarded Student Apr 23 awarded Yearling Mar 2 comment Water in an evacuated tube travels 10.3 meters. How does less water in the tube not violate some equilibrium condition? "we all have experienced..." no we have not. If the water rises less than 10.3 m, then there must be air trapped in the tube above the water, that is, it does not have vacuum above the water. Jan 29 answered The relation between Internal Pressure and flow rate in a balloon Jan 29 answered If we connect a long wire to a battery, will battery produce more electrons? Jan 29 awarded Enlightened Jan 29 awarded Nice Answer Jan 23 answered pressure as resistance Jan 22 answered How fast would an object have to move to create a vacuum behind it? Jan 21 answered Has $E=mc^2$ been experimentally verified for macroscopic objects with potential energy? Jan 16 comment What is potential energy truly? Energy has a finite weight, including potential energy, given by $E=mc^2$. Pretty amazing for something that you say isn't a substance. Jan 16 comment Where is the potential energy saved? @Time4Tea plato.stanford.edu/entries/equivME/#4 discusses measurements. Nothing as satisfying as weighing a compressed spring and comparing it to the weight of the uncompressed spring. Jan 14 comment Where is the potential energy saved? This is not right. Because of E=mc^2, the potential energy has an actual mass which with a fine enough scale can be measured. A 1 m on a side box sitting on earth with a 1 kg mass inside it at its top weighs slightly more than a 1 m on a side box sitting on earth with a 1 kg mass in it on its bottom. It weighs mgh/c^2 more where h is 1 meter and m is 1 kg. Sep 24 awarded Autobiographer Jun 8 comment Maximum theoretical efficiency of internal combustion engine @Simon yes gasoline routinely heats things up much higher than its combustion temperature. Combustion temperature is threshold for oxidation, but heat released by oxidation can easily heat things to many times that temperature. May 9 awarded Scholar May 9 accepted Why does hydrogen give up its electron to a platinum catalyst? Apr 30 answered Does a photon travel through space exactly at the speed of light? Apr 30 comment Why does hydrogen give up its electron to a platinum catalyst? Every picture I see does NOT show H or H2 being adsorbed on the platinum anode, but rather the electron from the H going in to the platinum anode and the $H^+$ running away from the platinum so it can diffuse across the membrane and show up at the cathode.