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Both energy and torque can be expressed as a product of a force vector with a displacement vector (hence pounds and feet); energy is the scalar product of the two, and torque is the vector product. Although calling the torque unit "pound-foot" has been academically suggested, both are still commonly called "foot-pound" in colloquial usage.
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion.The ton of TNT is a unit of energy defined by convention to be 4.184 gigajoules (1 gigacalorie), [1] which is the approximate energy released in the detonation of a metric ton (1,000 kilograms) of TNT.
Conversions between units in the metric system are defined by their prefixes (for example, 1 kilogram = 1000 grams, 1 milligram = 0.001 grams) and are thus not listed in this article. Exceptions are made if the unit is commonly known by another name (for example, 1 micron = 10 −6 metre).
In the US, torque is most commonly referred to as the foot-pound (denoted as either lb-ft or ft-lb) and the inch-pound (denoted as in-lb). [ 17 ] [ 18 ] Practitioners depend on context and the hyphen in the abbreviation to know that these refer to torque and not to energy or moment of mass (as the symbolism ft-lb would properly imply).
The British imperial units and U.S. customary units for both energy and work include the foot-pound force (1.3558 J), the British thermal unit (BTU) which has various values in the region of 1055 J, the horsepower-hour (2.6845 MJ), and the gasoline gallon equivalent (about 120 MJ). Log-base-10 of the ratios between various measures of energy
To calculate the foot-pound force (ft•lb f) of energy for a bullet in English units of measure; given bullet weight in grains and velocity in feet per second, use the following formula. E t = w • v² / ( 2 • g c • 7000 )
Conversion of the Mach unit of speed depends on the altitude at which the speed is measured. That altitude should be specified either in feet (for example, |altitude_ft=10,000) or in metres (for example, |altitude_m=3,749). The altitude cannot be determined accurately and only a whole number is accepted. Examples:
The foot-poundal (symbol: ft-pdl) is a unit of energy, introduced in 1879, that is part of the Absolute English system of units, which itself is a coherent subsystem of the foot–pound–second system. [1] The foot-poundal is equal to 1/32.174049 that of the more commonly used foot-pound force.