Fundamentals of Rocket Science :: physics rocket science

LiftoffRocket engines are different from car or jet engines in both fudamental ways. 1. Unlike cars, rockets dont need to push off of anything to propel themselves forward. 2. Rockets are self-contained. In other words they dont need oxygen from the atmosphere to provide fuel for energy.Rockets serve using the law of conservation of linear momentum. This law states that whenever two or more particles interact, the total momentum of the system remains constant. In this case the boo and its fuel can be considered separate particles.A rocket triggers by ejecting its fuel out the nose at extremely high velocities (approx. 6000 mph). The fuel is granted momentum as it is being ejected. To correspond conservation of linear momentum, the shuttle must be given a compensating momentum in the opposite direction.Rockets move exactly like Dr. Newman would if he were on a sheet of ice with 3 million pounds of baseb tout ensembles throwing them at a rate of 22,000 lbs/sec. Actually Dr. N ewman would move quite a a bit faster, because he has MUCH less mass than the space shuttle.To quickly summarize, thrust is equal to the exhaust pep pill multiplied by the bill fuel leaving with respect to time. This is illustrated by the equationThrust = ve(dM/dt)This tells us the only way to increase the amount of thrust acting on the rocket, is by increasing the velocity of the exhaust, or the amount of fuel, M, leaving per second. * This is why space shuttles dont hurl baseballs out the back of the rockets. Its takes a lot of energy to accelerate a baseball to 6000 mphRocket Scientist (they dont call them that for nothing) prefer to use the ideal gas law An ideal gas is one for which PV/nT is constant at all pressures. * Fuel and an Oxidizing agent, usually liquid oxygen and hydrogen respectively, are forced into the combustion chamber where they are ignited. The temperature increases which forces the pressure in the chamber to increase to insure PV/T remains constant.V olume inside the chamber is constant soPi/Ti = Pf/Tf, = Pf = PiTf/TiUsing Bernoullis equation we can determine the velocity of the gas exiting the NozzleVe = Ac2(Pc - Pn)/(p(Ac2-An2))(1/2)where V = velocity, A = cross sectional area, P = pressure, p = density of the fluid, and n,c = defines Nozzle and Combustion Chamber respectively.The final step is to visit the rate the mass is being ejected (dM/dt).