This model illustrates the law of conservation of momentum using jet propulsion as an example. The graph displays the change in rocket speed over time. The relative speed u of gas ejection from the rocket is assumed to be constant. Modify the mass M_{f} of the fuel in the rocket and watch the rocket?s acceleration until the fuel completely burns out. Note that after no more fuel is left, the rocket starts moving with a constant velocity. Try to determine what ratio of the initial and of the final masses M_{0}/M is required for the rocket to reach orbital velocity (at the given propulsion speed). Check your result using the Tsyolkovsky formula.