tech99's latest activity
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tech99 replied to the thread I Lightning rods -- how confusing can they be?.Regarding the size of conductor, 50mm^2 copper strip will carry nearly all strikes without damage, and something like 10mm^2 will carry... -
tech99 replied to the thread I Lightning rods -- how confusing can they be?.Although we can demonstrate the ionising action of a point in the laboratory, practical experience says that the shape of the lightning...
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The problem with the cosine and sine rule technique for vector arithmetic, is that there are too many opportunities to get a sign wrong...
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tech99 replied to the thread Vector/Phasor Addition.If you sketch the triangle it can be solved using, first, the cos rule to find ther unknown length of side:- a^2 = b^2 +c^2 - 2 bc cos A...
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tech99 replied to the thread B Ultrasonic wave and regular sound wave.You can see from the reply by nasu #4 that your first formula applies at all frequencies.
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tech99 replied to the thread B Simple mass/scale puzzle.Or the supposed impossibility of moving an object because every applied force has an equal and opposing reaction.
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tech99 replied to the thread B Simple mass/scale puzzle.Aftyer all that, as we measure weight in Newtons, the question is meaningless.
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tech99 replied to the thread B Ultrasonic wave and regular sound wave.I think gamma here is the ratio of the adiabatic to isothermal values for specific heat capacity. I will try to find out if there is a...
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tech99 replied to the thread How Does Flickering Light Influence Our Brain's Perception of Image Brightness?.The USA adopted 60 fields per second, 30 frames, and UK and Europe adopted 50 fields per second, 25 frames. These were initially locked...
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tech99 replied to the thread Capacitor charging: Where do extra electrons come from?.When the switch is operated, a pulse of opposite polarity is sent at the speed of light along each wire to the capacitor. The pulses...
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tech99 replied to the thread I Color and appearance of a "pile" of biological viruses.I think that the strongly coloured crystals are of ionic compounds, such as Copper, Iron and Cobalt. This seems to be because the ions...
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A couple of quotes from a late forum member which seem prescient. I’m sure most could guess who it is: 2016 re: traditional steam...
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tech99 replied to the thread Spain’s power outage.The beat frequency causes the destruction of the generators.
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tech99 replied to the thread Medical Are there theories of medicine that are under the umbrella of Physical Sciences?.Harvey, the circulation of the blood. The physics of pressure and flow.
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tech99 replied to the thread I Lightning rods -- how confusing can they be?.The lightning rod will provide a safe route to earth for a strike in its vicinity. As Tom G mentions, the protection cone is 30 to 60...
