PHYS 157 Lecture 19: PHYS 157 Lecture 19
PHYS 157 verified notes
19/26View all
Document Summary
Topics for today: review of entory stuff; and refrigerators: reversal of engine, basic notions in periodic motions: Kinematics, frequency, amplitude; displacement versus velocity iclicker questions for review. What is the efficiency of this carnot cycle? (t h - t c )(s b -s a ) A carnot engine is run between temps tsubh (hot reservoir) and tsubc (cold reservoir). A: 1-t c /t h, 1-t h /t c, not enough information given. Now with the same reservoirs, an engine instead works between t_1 (t_c) but following the same cycles and same compression ratio. The efficiency here is: lower, higher, same as the carnot engine. Large amount of 100c steam is used to melt ice at 0c. ice absorbs 5000j from the steam before it is completely melted. The change of the total entropy (of ice and steam) is: larger than zero, smaller than zero, equal to zero.
