The masses of blocks a and b in fig. p5.126 are 20.0 kg and 10.0 kg, respectively. the blocks are initially at rest on the floor and are connected by a massless string passing over a massless and frictionless pulley. an upward force is applied to the pulley. find the accelerations of block a and of block b when f is (a) 124 n; (b) 294 n; (c) 424 n.

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?