A 1-mCi point source of 137Cs is located at the center of a sphere of concrete. The sphere has a diameter of 10 cm. The source emits photons of energy 0.662 MeV with a frequency of 0.845 per decay. (a) What is the total interaction coefficient of the concrete at the source photon energy

An electrical kettle is made out of stainless steel,weighs two pounds (when empty) with a heating element that consumes 2 kw of electricity. assuming that the water and the kettle are at the same uniform temperature at any moment of time, calculate the shortest possible time to bring 2 quarts of water from room temperature to the onset of boiling.