Astronauts in orbit are apparently weightless. this means that a clever method of measuring the mass of astronauts is needed to monitor their mass gains or losses, and adjust their diet. one way to do this is to exert a known force on an astronaut and measure the acceleration produced. suppose a net external force of 50.0 n is exerted, and an astronaut’s acceleration is measured to be 0.893 m/s2 . (a) calculate her mass. (b) by exerting a force on the astronaut, the vehicle in which she orbits experiences an equal and opposite force. use this knowledge to find an equation for the acceleration of the system (astronaut and spaceship) that would be measured by a nearby observer. (c) discuss how this would affect the measurement of the astronaut’s acceleration. propose a method by which recoil of the vehicle is avoided.