Derek and Wes take a photograph of a lake at the same angle and the same time of day. Derek's picture comes out with crisp edges around objects in the photo. Wes's picture seems to blur the outlines of objects due to glare. Which wave phenomenon best explains the differences between the pictures?
a. diffraction
b. dispersion
c. reflection
d. polarization

On a mild saturday morning while people are working inside, the furnace keeps the temperature inside the building at 23degreesc. at noon the furnace is turned off, and the people go home. the temperature outside is a constant 16degreesc for the rest of the afternoon. if the time constant for the building is 3 hr, when will the temperature inside the building reach 18degreesc? if some windows are left open and the time constant drops to 2 hr, when will the temperature inside reach 18degreesc?