Bolt torque and clamp load across the published nut factors
A tightening torque becomes clamp load through a nut factor, K, that stands in for thread and head friction. On one M12...
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Hazen-Williams C values and how far the published tables disagree
Hazen-Williams estimates friction loss in a water pipe from one roughness number, C, and published tables give a cement-...
Horsepower, PS and kilowatts, and where the torque and power curves cross
Car power is printed in mechanical horsepower, metric horsepower (PS) or kilowatts, three units that differ by small fix...
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The clock rule taught for crosswind reads high, most of all at sixty degrees
The crosswind on a runway is the wind speed times the sine of the angle between wind and runway, and flight training tea...
Warm water shifts a pipe's Reynolds number more than the laminar limits differ
Physics texts put the end of laminar pipe flow at a Reynolds number of 2,000 or 2,300, depending on the source, and Reyn...
Jet lag by direction, worked through on routes out of Singapore and Hong Kong
Flying east asks the body clock to run earlier and flying west asks it to run later, and early estimates from real fligh...
Dog pregnancy length and why counting from mating widens the due date
A dog's pregnancy averages about 63 days counted from ovulation, but how wide the window is depends on which event start...
Rebar weight by the d²/162 rule runs a fraction heavy against the standards
Rebar mass per metre is usually worked out as the bar's diameter in millimetres, squared, divided by 162. We checked tha...
An X chromosome comes from fewer ancestors than a family tree allows
A man's X chromosome can come only from his mother's side, while a woman's comes from both parents, so the ancestors who...
Shortcut WBGT formulas land on both sides of Singapore's measured heat stress
Singapore's official heat stress readings blend three thermometers, one of them in the sun. Checked against 30 MSS stati...
Humidity adds close to 400 feet to density altitude at Changi
Water vapour is lighter than dry air, so humid air raises density altitude even at a sea-level airport. At Changi's Apri...
Homebrew ABV formulas part ways once original gravity reaches 1.070
Homebrewers turn original and final gravity readings into alcohol by volume with one of two formulas, which agree closel...
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