Are my answers right? 31: What does the term half life mean?

A: The time required for half of something to undergo a process.

32: The half-life of plutonium-239 is 24,300 years. If a nuclear bomb
released 8 kg of this isotope, how many years would pass before the
amount is reduced to 1 kg?

A: It would be 72,900 years.

33: The half-life of radon-222 is 3.8 days. How much of a 100 gram
sample is left after 15.2 days?

A: It would be 6.5 g of radon-222 is left over after 15.2 days.

34: Carbon-14 has a half-life of 5,730 years. If a sample contained 70 mg originally, how much is left after 17,190 years?

A: It would be 8.75 g of C-14 will be left.

35: The half-life of cobalt-60 is 5.26 years. If 50 grams are left after 15.78 years, how many grams were in the original sample?

A: The original sample will contain 400 gms of sample.

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

Which process is represented by the pv diagram? a. the isobaric process b. the isovolumetric process c. the isothermal process d. the adiabatic process

Aracecar driver has to hold on tightly when going around a banked curve. approximately what is the centripetal force on a 2220.0 kg car going around a circle with a diameter of 190.0 meters at 25.0 m/s?