Consider the video tutorial you just watched. suppose that we repeat the experiment, but this time we replace the original 56-g magnet with a more powerful magnet of the same mass. as you know from experience, the more powerful a magnet is, the more strongly it attracts or repels other magnets or magnetic objects. you have also probably noticed that magnetic forces fall off sharply with distance—two magnets that interact strongly across a distance of millimeters interact more weakly at a distance of a centimeter. (in fact, the strength of the force falls off with the square of the distance.) compared to the magnet in the video, the magnet in part a will hover at a position compared to the magnet in the video, the magnet in part a will hover at a position 1- farther above the base. 2- at the same distance above the base. 3- closer to the base.

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

If angle "a" is 25°, angle "b" is: a) equal to angle c b) less than angle c c) greater than angle c

Asilver dollar is dropped from the top of a building that is 1324 feet tall. use the position function below for free-falling objects. s(t) = −16t2 + v0t + s0 (a) determine the position and velocity functions for the coin. s(t) = v(t) = (b) determine the average velocity on the interval [1, 2]. ft/s (c) find the instantaneous velocities when t = 1 second and t = 2 seconds. v(1) = ft/s v(2) = ft/s (d) find the time required for the coin to reach the ground level. (round your answer to three decimal places.) t = s (e) find the velocity of the coin at impact. (round your answer to three decimal places.) ft/s