PLEASE HELP! I have a low fever and I am too sick to do anything so can anyone help me please answer these questions? 1: Why were Tycho and Kepler a good team?
2: How did changing the shape of the planet orbits help Kepler explain planetary movement?
3: What is an ellipse?
4: Does Kepler’s 2nd Law of Planetary Motion apply to satellites? Why or why not?

Thank you for helping me! you saved my life and my grade. :)

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?