A 200 kg weather rocket is loaded with 100 kg of fuel and fired straight up. It accelerates upward at 39 m/s2 for 26 s, then runs out of fuel and the rocket coasts. Ignore any air resistance effects and use -9.80 m/s2 for the local acceleration due to gravity. What is the rocket's maximum altitude (in km)? How long (in seconds) is the rocket in the air before hitting the ground?