College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 44

An alien spaceship traveling 0.600 c toward Earth launches a landing craft with an advance guard of purchasing agents. The lander travels in the same direction with a velocity 0.800 c relative to the spaceship. As observed on Earth, the spaceship is 0.200 light-years from Earth when the lander is launched. (a) With what velocity is the lander observed to be approaching by observers on Earth (b) What is the distance to Earth at the time of lander launch, as observed by the aliens on the mother ship (c) How long does it take the lander to reach Earth as observed by the aliens on the mother ship (d) If the lander has a mass of 4.00 × 10 5 kg, what is its kinetic energy as observed in Earth's reference frame