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Symbol | Definition |
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≡ | exactly equal |
≈ | approximately equal to |
= | equal to |
digits | indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) |
The foot-poundal (symbol: ft-pdl) is a unit of energy that is part of the foot-pound-second system of units, in Imperial units introduced in 1879, and is from the specialized subsystem of English Absolut (a coherent system). The foot-poundal is equal to 1/32.174049 that of the more commonly used foot-pound force.
The yottajoule (YJ) is equal to one septillion (1024) joules. This is approximately the amount of energy required to heat all the water on Earth by 1 °C. The thermal output of the Sun is approximately 400 YJ per second.