On Tuesday, 7 June 2022 at 14:25:31 UTC+2, a a wrote:
> On Tuesday, 7 June 2022 at 14:18:59 UTC+2, WM wrote:
> > W dniu 2022-06-07 o 01:17, Robert Tomasik pisze:
> > > W dniu 06.06.2022 o 22:49, WM pisze:
> > >>>> Niewiele krajów produkuje hel, więc mamy atut, który powinniśmy
> > >>>> wykorzystać i robić sterowce.
> > >>> Ja się kiedyś zastanawiałem nad patrolowaniem przez Policję takim
> > >>> sterowcem w nocy. Odpowiednie głowice optyczne i lot na tyle wysoko,
> > >>> by nie było sterowca łatwo z ziemi dostrzec. jak wyłączy silniki.,
> > >>> top w zasadzie niewidzialny i darmowy. Prędkość maksymalna i o, że
> > >>> leci po prostej powinna wystarczyć do większości pościgów. Zdolność
> > >>> lądowania
> > >> Dobry pomysł, można mu dodatkowo zamontować fotoradar.
> > >
> > > Nie można, bo za wysoko. Natomiast ciekawe, czy jako BSL by mógł działać.
> > >
> > Można porównywać klatki filmu, jak to robi mysz optyczna.
> > Gorzej z identyfikacją, bo jeszcze nikt nie pomyślał o tablicach
> > rejestracyjnych na dachach samochodów.
> > Jednak system sterowca połączony z kamerami na skrzyżowaniach załatwia
> > sprawę.
> > Totalny fotoradar miejski i mamy radykalne zmniejszenie wypadków.
> > Taki dopracowany system: sterowiec + kamery to potencjalny super towar
> > eksportowy.
> >
> > WM
> https://www.engineeringtoolbox.com/helium-density-sp
ecific-weight-temperature-pressure-d_2090.html
> Helium - Density and Specific Weight vs. Temperature and Pressure
> Online calculator, figures and tables showing density and specific weight of
helium, He, at varying temperature and pressure - Imperial and SI Units.
> Sponsored Links
>
> Density, ?, has units typically [kg/m3] or [lb/ft3], and is defined by the ratio of
the mass to the volume of a substance:
>
> ? = m/V [1]
>
> where m = mass, units typically [kg] or [lb]
> V = volume, units typically [m3] or [ft3]
>
> Specific weight, ?, has units typically [N/m3] or [lbf/ft3] is defined by the ratio
of the weight to the volume of a substance:
>
> ? = (m * g)/V = ? * g [2]
>
> dalej tabelki, wykresy i da się coś obliczyć

Helium Balloon and the effect of temperature on the volume of balloon
Submitted by cjc901 on Wed, 07/23/2008 - 01:12

If anybody could help me with this or show me a place where I could look to possibly
find the answer I would greatly appreciate it.

Thanks!

Qustion:
Helium-filled balloons will quickly begin to shrink and can no longer float when
taken from the store into the bitter cold of a winter day. However, the balloons will
quickly re-expand, float high and look as good as they did in the store when taken
into the warm house. A) Name the law that explains this phenomenon. B) Explain the
processes that were involved in the contraction and then re-expansion of the
balloons.

Submitted by spock on Wed, 07/23/2008 - 08:16
Permalink
Re: Helium Balloon

Balloons float as a result of differences in density. The density of a He balloon is
less than the density of air (this is because the molecules of He have less mass than
the molecules of O2 and N2 than make up air).

Density depends on two factors: mass and volume. The formula is density =
mass/volume

Changing the temperature of a balloon has no effect on the mass of the He inside the
balloon, but a decrease in temperature WOULD have an effect on the volume of the gas
in the balloon according to CHARLES' LAW (which states that volume is directly
related to the temperature of the gas at constant pressure). So, if I lower the
temperature of the gas, I will cause the volume of the gas to decrease, which will
increase the density of the He gas. Since the He becomes less dense relative to the
air, its buoyancy will decrease and will not float as well. Returning the
temperature of the gas molecules to the original higher level will cause the volume
to increase, thus decreasing the buoyancy.

The kinetic molecular theory allows for an explanation of the above phenomena. As
the temperature of the gas molecules increase the molecules will move faster and hit
the sides of the balloon harder. This causes the He gas to exert a greater pressure
on the inside of the balloon. Since the pressure on the outside of the balloon is
essentially the atmospheric pressure, which is constant, the balloon will expand
until the pressure of the He on the inside is once again equal to the pressure of the
air. This causes the increase in volume (and resultant increase in buoyancy) that we
talked about above when the balloon was returned to the warm room.

Submitted by cjc901 on Wed, 07/23/2008 - 09:41
Permalink
Re: Helium Balloon

Thank you very much!

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