1. An astronaut of 100 kg at 100 meters from his spaceship finds himself hopelessly drifting away at a speed of 9.07 m/s, he decides to throw a heavy wrench (10 kg) to rescue himself. With what speed (relative to himself) does he need to throw the wrench in order to slow down by 20% of the initial drifting speed (albeit still drifting away)? Note: world record of baseball pitch is over fifty meter per second.