18) An astronaut massing 75kg, suit, tools, and all, is performing maintenance on a space station, at rest. The astronaut accidently throws a 4kg wrench in their hand directly towards the space station hull at 13ms. a) What does NIII tell you about the force exerted on the astronaut by the act of throwing this wrench? b) What is the velocity of the astronaut after losing their wrench and why is the tether attaching them to the space station a life saving device?