Suppose there are two twins, Greg and Sam. Greg stays on Earth and Sam travels to the stars as a scientist. Space travel has advanced to the point where spaceships can travel through the universe at speeds close to the speed of light. When Sam returns to Earth, how would the twins’ ages compare?

a. sam would be older
b. sam would be younger
c. sam and greg would be the same age

What is the momentum of a 2 kg object moving at 15 meters per second

Cyclotrons are widely used in nuclear medicine for producing short-lived radioactive isotopes. these cyclotrons typically accelerate h- (the hydride ion, which has one proton and two electrons) to an energy of 5 mev to 20 mev. this ion has a mass very close to that of a proton because the electron mass is negligible—about 1 2000 of the proton’s mass. a typical magnetic field in such cyclotrons is 1.9 t. (a) what is the speed of a 5.0-mev h-? (b) if the h- has energy 5.0 mev and b = 1.9 t, what is the radius of this ion’s circular orbit?

Why should the wavelength scale of spectroscope be calibrated