A spaceship is cruising at constant speed v - 0.5e as seen from an inertial ob- server in S'. A pie of rest mass m“ = 9kg is thrown at a speed ue - 0.8c as seen from the spaceship pilot and collides with a second pie (initially at rest) of rest mass 7kg, after which the two pies stick together. 1. What is the momentum of the first pie before collision (as seen by the spaceship pilot)? 2. What is the speed of the two pies together after collision according the spaceship pilot and the observer in S'? 3. If the pies are radioactive with rest half-lifetime ro 10" years, how long will it take according to the spaceship pilot for half of the pie atoms to decay?

A spaceship is cruising at constant speed v - 0.5e as seen from an inertial ob- server in S'. A pie of rest mass m“ = 9kg is thrown at a speed ue - 0.8c as seen from the spaceship pilot and collides with a second pie (initially at rest) of rest mass 7kg, after which the two pies stick together. 1. What is the momentum of the first pie before collision (as seen by the spaceship pilot)? 2. What is the speed of the two pies together after collision according the spaceship pilot and the observer in S'? 3. If the pies are radioactive with rest half-lifetime ro 10" years, how long will it take according to the spaceship pilot for half of the pie atoms to decay?