Two rooms, each a cube 4.0m per side, share a 14-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air is at 31 Degrees C, while in the other room it is at 11 degrees C. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s.part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.