A84.5 kg astronaut is working on the engines of a spaceship that is drifting through space with a constant velocity. the astronaut turns away to look at earth and several seconds later is 38.9 m behind the ship, at rest relative to the spaceship. the only way to return to the ship without a thruster is to throw a wrench directly away from the ship. the wrench has a mass of 0.613 kg, and the astronaut throws the wrench with a speed of 24.9 m/s. how long does it take the astronaut to reach the ship? answer in units of s.