The hot water needs of a residence are met by a 20-gal hot water heater rated at 6000 btu/h. the tank is initially filled with hot water at 175°f. as the hot water supply is drawn from the tank, it is replaced by cold water at 50°f at a flow rate sufficient to keep the tank full at all times. during this replenishing process in the tank, the water is heated at the water heater’s full rated capacity. water this hot is great for washing clothes or dishes, but it is far t

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?