When radio waves try to pass through a city, they encounter thinvertical slits: the separations between the buildings. this causesthe radio waves to diffract. in this problem, you will see howdifferent wavelengths refract as they pass through a city andrelate this to reception for radios and cell phones. you will usethe angle from the center of the central intensity maximum to thefirst intensity minimum as a measure of the width of the centralmaximum (where nearly all of the diffracted energy isfound). consider radio waves of wavelength λ entering a city where the buildings have an average separation of a. part a find the angle θ to the first minimum from the center of the central maximum. express your answer in terms of λ and a

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 free body diagram shows a box being pulled to the left up a 25-degree incline. the magnitude of the normal force is

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j? 1. write the equation 2.list out your known variables 3.plug the numbers into the equations 4.solve 5.write your solution statement that includes initial energy and final