Water Rocket Computer Model Help
 Rocket Environment Unless you are seeing what it would be like to launch on a different planet or use a different liquid or gas, you wouldn't normally need to change any of the parameters in this box. However... Gamma: the compresibility of a gas depends upon its molecules - whether the gas is made from single atoms, for example with the noble gasses, He, Ne, Ar etc or diatomic molecules such as O2, N2, Cl2 or more complex molecules such as CH4, CO2, C2H6, C3H6, C3H8 and so on. The value is the ratio of heat capacities at constant volume and constant pressure and is in effect how springy it is. Example values are: Air = 1.402; Ar = 1.662; He = 1.66; C2H6 = 1.26; and, CO2 = 1.304. Gas Density: the amount of gas in a given volume. Counter-intuitively, a particular volume will contain the same number of gas molecules regardless of what that gas is. In this way, we can work out density of a gas from its molecular weight (or atomic weight in the case of a monatomic gas). The magic volume is 22.4litres which contains one mole of gas. Another way of looking at it is that a cubic metre of gas at STP holds a little over 44.6 moles of gas so if you were going to use Xenon (cost is not an issue here...) - its atomic weight is 131.29 and it is a noble gas so its density would be 44.6 x131.29 = 5,956gm-3 or 5.956kgm-3. Example values are: Air = 1.293; Ar = 1.784; He = 0.179; C2H4 = 1.260; and, CO2 = 1.977. Liquid Density: This is the density of the liquid at the ambient temperature. Example values are: Water = 998; Seawater = 1025; Hg = 13546; Olive Oil = 920, CCl4 = 1632; and, Br = 3100. Acceleration due to gravity: If you are thinking about how this rocket would perform on the Moon, Mars or some exoplanet, put the value in here. Example values are: Sun = 274; Moon = 1.62; Mercury = 3.76; Venus = 8.77; Earth = 9.81; Mars = 3.80; Jupiter = 24.9; Saturn = 10.4; Uranus = 10.4; Neptune = 13.8; and, Pluto = 4.0. Atmospheric Pressure: Insert the barometric pressure here. Note that this is the barometric pressure where you are launching from and not necessarily the pressure at lea level. If you are launching at high altitude, this can become relevant because it affects drag force on the rocket of the atmospheric air of its surroundings. Density of Atmospheric Gas Example values are: Air = 1.293; NH3 = 0.771; He = 0.179; H2 = 0.090; CH4 = 0.717; SO2 = 2.927; and, CO2 = 1.977. Note that if the air pressure is substantially lower or higher than that on Earth, still put the value at STP into the density but put the atmospheric pressure in the box above.