The reason carbon dating works is that a. there is so much non-radioactive carbon dioxide in the air. b. when a plant or animal dies, it stops producing oxygen. c. plants and animals are such strong emitters of carbon-14. d. after a plant or animal dies, it stops taking in fresh carbon-14. e. none of the above

Steam is generated in a boiler of a cogeneration plant at 10 mpa and 450°c at a steady rate of 5 kg/s. in normal operation, steam expands in a turbine to a pressure of 0.5 mpa and is then routed to the process heater, where it supplies the process heat. steam leaves the process heater as a saturated liquid and is pumped to the boiler pressure. in this mode, no steam passes through a condenser, which operates at 20 kpa. (a) determine the power produced in the turbine and the rate at which process heat is supplied in this mode. (b) determine the power produced in the turbine and the rate of process heat supplied if only 60 percent of the steam is routed to the process heater and the remainder is expanded to the condenser pressure. (3.32 mw; 9.69 mw; 4.25 mw; 5.82 mw)

Which of the following is not a transverse wave? a) soundb) lightc) radiod) all of thesee) none of these

Which of these has some mechanical energy? a. an atom b. heat inside earth c. a book on a shelf d. the fire from a lit match