In the early 1990s, Lockheed Martin utilized a new thruster, the hydrazine arcjet for North-South station keeping (NSSK) on its geostationary orbit satellites. The early R&D (through preflight qualification) on the hydrazine arcet was done at NASA Glenn
Research Center. The current production arcjet thrusters are manufactured by Aerojet Redmond. The Lockheed Martin series 7000
satellites use the Aerojet MR 509 hydrazine arcjet system (1.8 kW power level, Isp of 502 sec). The archet continues to evolve with the
latest Lockheed satellite bus, the A2100 satellites, which utilize the MR-510 arcjet system (2.2 kW, 582-sec nominal Isp thrusters) for
NSSK. Again, the archet thruster takes advantage of the higher satellite power available to substantially increase the performance
over catalytic hydrazine (Isp = 225 sec to Isp = 570 to 600 sec).

Tom is having a problem with his washing machine. he notices that the machine vibrates violently at a frequency of 1500 rpm due to an unknown rotating unbalance. the machine is mounted on 4 springs each having a stiffness of 10 kn/m. tom wishes to add an undamped vibration absorber attached by a spring under the machine the machine working frequency ranges between 800 rpm to 2000 rpm and its total mass while loaded is assumed to be 80 kg a) what should be the mass of the absorber added to the machine so that the natural frequency falls outside the working range? b) after a first trial of an absorber using a mass of 35 kg, the amplitude of the oscillation was found to be 10 cm. what is the value of the rotating unbalance? c) using me-3.5 kg. m, find the optimal absorber (by minimizing its mass). what would be the amplitude of the oscillation of the absorber?