Light enters a Newtonian reflection telescope and hits a mirror inside the telescope to redirect the light to the eyepiece. The light strikes the mirror at an angle of 45 degrees. What angle is it reflected back off the mirror towards the eyepiece?

A) 15 degrees
B) 45 degrees
C) 90 degrees
D) 180 degrees

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?