1. Preparing for reentry, astronauts use radar to determine the distance back to the earth. What is their altitude if it takes 0.330 s for the radar wave to travel to the earth and return?
2. The distance to the moon can be calculated by reflecting a ray of light off a mirror left by astronauts. The light travels to the mirror and back in 2.56 s. find the distance to the moon.
3. Light from the sun travels 1.50 x 108km to reach the earth. How long does its journey take in minutes?