Ameter-long ruler (meterstick) has a mass of 200 g giving it a weight of 1.96 n (nearly 1/2 pound). a pencil lying flat on a tabletop serves as a fulcrum, and if the ruler is placed with the 50-cm mark above the pencil the ruler is balanced – showing that the center of mass is at the center of the ruler.

a) draw a diagram showing the ruler placed horizontally on the pencil with the ruler's 35- cm mark above the pencil. draw vectors showing the two forces that act on the ruler (weight and normal force) at the instant it is released (we realize, of course, that the ruler will quickly be rotationally accelerated by the net torque).
b)as you have drawn it above, is the torque acting on the pencil clockwise (cw) or counterclockwise (ccw)?
c)what is the magnitude of the torque acting on the ruler?

An internally reversible refrigerator has a modified coefficient of performance accounting for realistic heat transfer processes of where qin is the refrigerator cooling rate, qout is the heat rejection rate, and is the power input. show that copm can be expressed in terms of the reservoir temperatures tc and th, the cold and hot thermal resistances rt,c and rt,h, and qin, as where rtot rt,c rt,h. also, show that the power input may be expressed as 1.39 a household refrigerator operates with cold- and hot-temperature reservoirs of tc 5 c and th 25 c, respectively. when new, the cold and hot side resistances are rc,n 0.05 k/w and rh,n 0.04 k/w, respectively. over time, dust accumulates on the refrigerator’s condenser coil, which is located behind the refrigerator, increasing the hot side resistance to rh,d 0.1 k/w. it is desired to have a refrigerator cooling rate of qin 750 w. using the results of problem 1.38, determine the modified coefficient of performance and the required power input w under (a) clean and (b) dusty coil conditions. internally reversible refrigerator qout qin w high-temperature reservoir low-temperature reservoir th th,i tc,i tc high-temperature side resistance low-temperature side resistance w qin th tc qinrtot tc qinrtot copm tc qinrtot th tc

The earth is constantly spinning on its axis, like you might spin a basketball on your finger. it is this spinning of the earth that causes

How much energy must a refrigerator absorb from 225 g of water so that the temperature of the water will drop from 35°c to 5°c