# G in fps

### What is a "g"

#### Summary: The term g is based on the pull of gravity.

NASA had a definition in their 1965 dictionary of Technical Terms for Aerospace Use:

g or G

An acceleration equal to the acceleration of gravity, 980.665 centimeter-second-squared, approximately 32.2 feet per second per second at sea level; used as a unit of stress measurement for bodies undergoing acceleration. See acceleration of gravity; gravity.

acceleration of gravity (symbol g)

By the International Gravity Formula, g = 978.0495 [1 + 0.0052892 sin2(p) - 0.0000073 sin2 (2p)] centimeters per second squared at sea level at latitude p. See gravity. The standard value of gravity, or normal gravity, g, is defined as go=980.665 centimeters per second squared, or 32.1741 feet per second squared. This value corresponds closely to the International Gravity Formula value of g at 45 degrees latitude at sea level.

and another in a newer publication, this one still available on the web:

Acceleration

A dropped object starts its fall quite slowly, but then steadily increases its velocity--accelerates--as time goes on. Galileo showed that (ignoring air resistance) heavy and light objects accelerated at the same constant rate as they fell, that is, their speed (or "velocity") increased at a constant rate. The velocity of a ball dropped from a high place increases each second by a constant amount, usually denoted by the small letter g (for gravity). In modern units (using the convention of algebra, that symbols or numbers standing next to each other are understood to be multiplied) its velocity is

at the start -- 0 (zero)
after 1 second-- g meters/second
after 2 seconds-- 2g meters/second
after 3 seconds-- 3g meters/second

and so on. This is modified by the resistance of the air, which becomes important at higher speeds and usually sets an upper limit ("terminal velocity") to the fall velocity--a much smaller limit for someone using a parachute than one falling without.

The number g is close to 10--more precisely, 9.79 at the equator, 9.83 at the pole, and intermediate values in between--and is known as "the acceleration due to gravity." If the velocity increases by 9.81 m/s each second (a good average value), g is said to equal "9.81 meters per second per second" or in short 9.81 m/s2.

Got that?

In layman's terms, g is the amount of gravity the earth exerts on you when you fall. Spacemen float around at near zero g when they get up there in orbit. You experience 1 g for your whole life on earth except on those carnival rides where you float and your stomach turns upside down. Or you can encounter much, much more than one g when you fall and hit your head.

Since you fall according to gravity, and the gravity is a constant on earth, you know how hard you are going to hit when you fall from two meters with no forward speed. That's about 14 miles per hour, and that's the drop used in a lab to test bike helmets hitting flat surfaces for the US CPSC standard. (We have the speed calculations on another page.) Forward speed can add some to that, but not much if your helmet skids on the pavement the way it should and does not snag. If it snags, all bets are off, since lab tests show that the result can be more g's to the brain as well as a strain on your neck. That's why you will see us emphasize that the outside of a helmet should be round and smooth to skid well on pavement.

Without a helmet, hitting your head can transmit a thousand or more g's to your brain in about two thousandths of a second as you come to a violent, very sudden stop on the hard, completely unyielding pavement. With a helmet between you and the pavement your stop is stretched out for about seven or eight thousandths of a second by the crushing of the helmet foam. That little bit of delay and stretching out of the energy pulse can make the difference between life and death or brain injury.

Helmets do not "absorb" energy. Nothing does. The law of energy conservation says that a helmet can transform energy to work or to another form of energy, but can't absorb it. That's why we refer to helmets as "managing" impact energy rather than absorbing it.

Along with the stretching out of the impact, a helmet does change a small amount of the energy of a blow to heat as the molecules of foam move in the crushing of the foam. To test that out for yourself, take a piece of picnic cooler foam on a hard surface and hit it with a hammer. The dent the hammer makes will be warm to the touch. And crushing foam is certainly work.

So all things being equal (red flag, they never are in real life!) a thicker helmet can stop you more gradually than a thin one. It just has more distance to bring your head to a stop. (an inch, maybe, vs. a half inch). And the foam in a thinner helmet has to be firmer to work without being completely crushed right away in a hard impact. So in a softer impact it may not crush at all. For a softer landing in the full range of impacts, you want a helmet that has less dense foam and more thickness. But just try to find that on the market! Things get further complicated when the designer decides that the rider will pay more for bigger vents and a thinner helmet. Those big vents reduce the amount of foam in the helmet and require harder foam in the spots that are left. So sometimes you might get better impact protection from a cheaper helmet with thicker foam and smaller vents. But sometimes you might not, since all things are never equal in the real world.

A note on "acceleration." The hard core physics types who populate helmet labs and helmet standards committees insist on using the scientifically-correct term acceleration to describe what happens when the head hits the pavement. Not deceleration as you might expect if you speak plain English. So they will write their descriptions as g's of acceleration of the head relative to the pavement. If you are not an engineer, just translate that to deceleration. Engineers will smirk, but people will always understand you.

For more on helmet design, we have a page up on the ideal helmet.

For more on g's, see a textbook on physics.

Sours: https://www.helmets.org/g.htm

FPS stands for Feet Per Second, for those of you who hate anything other than SI units (Systeme Internationale), one fps is 0.304 meters/sec, (equivalently 1m/s = 3.28 fps). This is why 328fps is thrown around as a limit. 328fps is 100m/s, and a 0.2g bb travelling at this speed possess the energy of exactly 1 Joule.

Energy (in joules) = 1/2 mass * velovity^2

How can I calculate my airsoft replica's energy?

Using this handy form you can calculate your replica's energy in joules. As a by-product it'll also give you your bb's velocity in m/s. To calculate the energy in joules, simply enter the mass of ammunition (in grams) that you use, and the fps that you've read from your chrono unit.

So how does extra FPS affect my range? Well I've been having a think about this, and we will be conducting some tests with some AEG's at some point in the warmer part of the summer, from these we'll be able to deduce some real-world figures. Right now though the easiest thing that I can do is calculate some range using basic physics, making certain assumptions. For starters we'll ignore hop-up, as we know it increases range, and I'm not going to sit here and work out higher level physics using specific air density and fluid dynamics - I'll do that later on =). This model assumes a curved flight path, I know hop-up produces a straighter path, but you'll be suprised how close the figures from this model match to real-life.

From basic physics, lets start with a basic equation:

 s = distanceu = initial velocityv = final velocitya = accelerationt = time passed s = ut + 1/2 at^2

Assume you are firing the bb from a height of 1metre (i.e. with your rifle shouldered), lets calculate the time it takes for your bb to drop and hit the ground:

 s = ut + 1/2 at^2 hence, 1 = 0 + (0.5* 9.81) * t^2 t = sqrt( 1/(0.5*9.81) ) t = sqrt(0.203...)t = 0.45 seconds (2SF)

Hence time taken to fall 1 metre is 0.45 seconds. With a velocity of 328fps or 100m/s, this mean your bb will travel (328*0.45)=148feet or 45metres before hitting the ground, giving you your effective range. If you don't know the energy of your rifle, you can either calculate it above, or use 1J as the limit for AEG's, and 2.31J as the limit for single action.

Sours: http://www.coderedairsoftpark.com/pages/park-rules-and-hours/fps-calculator.php

## Foot–pound–second system

Physical system of measurement that uses the foot, pound, and second as base units

The foot–pound–second system or FPS system is a system of units built on three fundamental units: the foot for length, the (avoirdupois) pound for either mass or force (see below), and the second for time.[1]

### Variants

Collectively, the variants of the FPS system were the most common system in technical publications in English until the middle of the 20th century.[1]

Errors can be avoided and translation between the systems facilitated by labelling all physical quantities consistently with their units. Especially in the context of the FPS system this is sometimes known as the Stroud system after William Stroud, who popularized it.[2]

### Pound as mass unit

When the pound is used as a unit of mass, the core of the coherent system is similar and functionally equivalent to the corresponding subsets of the International System of Units (SI), using metre, kilogram and second (MKS), and the earlier centimetre–gram–second system of units (CGS).

In this sub-system, the unit of force is a derived unit known as the poundal.[1]

The international standard symbol for the pound as unit of mass rather than force is lb.[5]

Everett (1861) proposed the metric dyne and erg as the units of force and energy in the FPS system.

Latimer Clark's (1891) "Dictionary of Measures" contains celo (acceleration), vel or velo (velocity) and pulse (momentum) as proposed names for FPS absolute units.

### Pound-force as force unit

The technical or gravitational FPS system,[6] is a coherent variant of the FPS system that is most common among engineers in the United States. It takes the pound-force as a fundamental unit of force instead of the pound as a fundamental unit of mass.

In this sub-system, the unit of mass is a derived unit known as the slug.[1]

In the context of the gravitational FPS system, the pound-force (lbf) is sometimes referred to as the pound (lb).

### Pound as force unit

Another variant of the FPS system uses both the pound-mass and the pound-force, but neither the slug nor the poundal. The resulting system is not coherent, lacking electrical or molar units, and is sometimes also known as the British engineering system, although rarely used nowadays in the United Kingdom.[6]

It stand for foot pound system which is used to measure the physical quantity in length mass and, time

### Molar units

The unit of substance in the FPS system is the pound-mole (lb-mol) = 273.16×1024. Until the SI decided to adopt the gram-mole, the mole was directly derived from the mass unit as (mass unit)/(atomic mass unit). The unit (lbf⋅s2/ft)-mol also appears in a former definition of the atmosphere.

### Electromagnetic units

The electrostatic and electromagnetic systems are derived from units of length and force, mainly. As such, these are ready extensions of any system of containing length, mass, time. Stephen Dresner[7] gives the derived electrostatic and electromagnetic units in both the foot–pound–second and foot–slug–second systems. In practice, these are most associated with the centimetre–gram–second system. The 1929 "International Critical Tables" gives in the symbols and systems fpse = FPS electrostatic system and fpsm = FPS electromagnetic system. Under the conversions for charge, the following are given. The CRC Handbook of Chemistry and Physics 1979 (Edition 60), also lists fpse and fpsm as standard abbreviations.

Electromagnetic FPS (EMU, stat-)
1 fpsm unit = 117.581866 cgsm unit (Biot-second)[clarification needed]
Electrostatic FPS (ESU, ab-)
1 fpse unit = 3583.8953 cgse unit (Franklin)
1 fpse unit = 1.1954588×10−6 abs coulomb

### Units of light

The candle and the foot-candle were the first defined units of light, defined in the Metropolitan Gas Act (1860).[8] The foot-candle is the intensity of light at one foot from a standard candle. The units were internationally recognized in 1881, and adopted into the metric system.[9]

### Conversions

Together with the fact that the term "weight" is used for the gravitational force in some technical contexts (physics, engineering) and for mass in others (commerce, law),[10] and that the distinction often does not matter in practice, the coexistence of variants of the FPS system causes confusion over the nature of the unit "pound". Its relation to international metric units is expressed in kilograms, not newtons, though, and in earlier times it was defined by means of a mass prototype to be compared with a two-pan balance which is agnostic of local gravitational differences.

In July 1959, the various national foot and avoirdupois pound standards were replaced by the international foot of precisely 0.3048 m and the international pound of precisely 0.45359237 kg, making conversion between the systems a matter of simple arithmetic. The conversion for the poundal is given by 1 pdl = 1 lb·ft/s2 = 0.138254954376 N (precisely).[1]

To convert between the absolute and gravitational FPS systems one needs to fix the standard accelerationg which relates the pound to the pound-force.[citation needed]

While g strictly depends on one's location on the Earth surface, since 1901 in most contexts it is fixed conventionally at precisely g0 = 9.80665 m/s2 ≈ 32.17405 ft/s2.[1]

### References

1. ^ abcdefCardarelli, François (2003), "The Foot–Pound–Second (FPS) System", Encyclopaedia of Scientific Units, Weights and Measures: Their SI Equivalences and Origins, Springer, pp. 51–55, ISBN .
2. ^Henderson, James B.; Godfrey, C. (1924), "The Stroud system of teaching dynamics", The Mathematical Gazette, 12 (170): 99–105, JSTOR 3604647.
3. ^Comings, E. W. (1940). "English Engineering Units and Their Dimensions". Industrial & Engineering Chemistry. 32 (7): 984–987. doi:10.1021/ie50367a028.
4. ^Klinkenberg, Adrian (1969). "The American Engineering System of Units and Its Dimensional Constant gc". Industrial & Engineering Chemistry. 61 (4): 53–59. doi:10.1021/ie50712a010.
5. ^IEEE Std 260.1™-2004, IEEE Standard Letter Symbols for Units of Measurement (SI Units, Customary Inch-Pound Units, and Certain Other Units)
6. ^ abJ. M. Coulson, J. F. Richardson, J. R. Backhurst, J. H. Harker: Coulson & Richardson's Chemical Engineering: Fluid flow, heat transfer, and mass transfer.
7. ^Dresner, Stephen (1971). Units of Measurement. New York: Hastings House. pp. 193–205.
8. ^Jerrard, H G (1985). A Dictionary of Scientific Units. London: Chapman and Hall. p. 24. ISBN .
9. ^Fenna, Donald (2003), Dictionary of weights and measures, ISBN
10. ^NIST Federal Standard 376B , p. 13. Archived August 16, 2010, at the Wayback Machine
Sours: https://en.wikipedia.org/wiki/Foot%E2%80%93pound%E2%80%93second_system

But she didn't have time. Instantly grabbing the hair with my other hand, I pulled back. You forget yourself. I wanted to reward you for quickly following my instructions, but now I will punish you. And you have to check how well you did everything.

## In fps g

No, without feeling any unpleasant sensations, I answered. What innocent we are, Lera babbled introducing the second finger. There was so much lubrication that I didn't feel any pain even now.

How to check FPS in Games? Msi Afterburner (Hindi)

Then he said to Lesha "Come closer, look!" I blushed all over with embarrassment, despite the fact that I was very excited. An almost unfamiliar guy looks. At me in this position. "Come on, beauty, don't break!" he said. "Oh, I have an idea!" said Slava.

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But I do not go to school alone, I have a school friend Andryukha, nicknamed Smell (this is not related to sniffing, it just went through. School), he is 22 years old, in the 5th grade he moved to our city from Ukraine, with my family. We ran the whole school with him and skipped, together we went to showdowns with the local boys, relaxed, fought the girls who had to be torn apart so.

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