In order to study the long-term effects of weightlessness, astronauts in space must be weighed (or at least 'massed'). One way to accomplish this task is to seat them in a chair of known mass attached to a spring with a known spring constant and measure the period of oscillation. The 39 kg chair alone oscillates with a period of 1.18 s, and the period with the astronaut sitting in the chair is 2.00 5. Find the mass of the astronaut