Astronauts at the ISS orbit around the Earth at about 8km/s. Thus, from the Earths perspective, the ISS experiences some amount of time dilation.
A. If an astronaut spends 60 years of their life on the ISS, how much time will have passed on Earth?
B. Two identical twins, Twin A and Twin B, are astronauts in training. Twin A is selected to go on the ISS for two years while Twin B remains on Earth. Eventually, Twin A returns to Earth. Are the siblings still the same age or has one aged more than the other?

Astronauts at the ISS orbit around the Earth at about 8km/s. Thus, from the Earths perspective,...
Many communication satellites are placed in a circular orbit around the Earth at a radius where the period (the time to go around the Earth once) is 24 hours. If the satellite is above some point on the equator, it stays above that point as the Earth rotates, so that as viewed from the rotating Earth the satellite appears to be motionless. That is why you see dish antennas pointing at a "fixed" point in space. (a) Calculate the radius...