49 tamela12 what is the efficiency of a device that takes in 40,000 j of heat and does 12,000 j of work while giving off 28,000 j of heat? use and convert to a percentage. a. 57% b. 43% c. 30% d. 70%

The temperature in gavin's oven is a sinusoidal function of time. gavin sets his oven so that it has a maximum temperature of 280°f and a minimum temperature of 240°. once the temperature hits 280°, it takes 20 minutes before it is 280° again. gavin's cake needs to be in the oven for 30 minutes at temperatures at or above 270°. he puts the cake into the oven when it is at 260° and rising. how long will gavin need to leave the cake in the oven? (round your answer to the nearest minute.)