F = dwater * volume flow * vel = 374.4 lbm ft/s 2į = 374.4 lbm ft/s 2 divide by 32.2 lbm-ft/lbf-s 2 = 11.examine a situation without gravity, the force produced by a jet of water. Lbm and lbf are not the same - they are only of the same value in one situation, when dealing with gravity at sea level. QUESTION: An astronaut has a mass of 100kg (220lbs) what is his weight (force) if he is on earth? what if he was on a planet with the gravity of 5m/s^2 (16.4ft/s^2)? On the surface of earth, 1lbm exerts a force of 1lbf. The MKS system of units is a physical system of measurement that uses the metre, kilogram, and second (MKS) as base units. On the surface of earth, 1kg exerts a force of 9.81N. Looking at the last two points above, it is obvious that the newton is very different that the lbf Think of pound-force (lbf) as the force required to move a mass of 1lbm by 32.2ft/s^s Force is measured using acceleration, mass, and speed. Think of newton as the force required to move a mass of 1kg by 1m/s^2 In simple terms, a Newton is the System International (SI) unit used to measure force. Once you understand this concept well you can go on to familiarize yourself to using slugs. One newton equals a force that produces an acceleration of one meter per second (s) per second on a one kilogram (kg. One joule equals the work done (or energy expended) by a force of one newton (N) acting over a distance of one meter (m). you will see lbm used in your text and in real life 99% of the time. The joule (symbol J) is the SI unit of energy a measure of the capacity to do work or generate heat. I know it is the standard unit for mass and so is lbm. I will try to make it as simple as possible and will provide an example: I'd suggest adopting sdl for (2) lbf with unit slug, the ambiguity of pound is an unusual punishment lb, lbs, lbm, lbf, lbf. Know the base units of your system, lbf will always be an ambiguity problem as long as it exists in its current symbolic form. In SI units, the force unit is the newton ($N$), and it is defined as the force required to accelerate a mass of $1\cdot kg$ at a rate of $1\cdot\fracĮssentially, (1),(2) and (3) are all dividing by 32.174049, however, it is when and how that makes all the difference.
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