Consider an observer oving to the right with velocity b relative to observer s. a rod of length l is at rest in s' and aligned with the relative velocity. observer s has learned from er textbook that if she records the positions of the ends of the rod at the same instant. she will find the rod to be foreshortened to length l/r. now s thinks to herself that maybe she can measure the proper length of the rod by adopting an alternative procedure in which easures the positions of the e nds of the rod no she m t at the same instant but at temporally distinct instants such that s 's clocks at the ends of the rod show the same time at the two instants. those clocks, after all, show the same time when s' measures the length of the rod. what does s find for the length of the rod using this method? does she fulfill her ambition' how does her result compare with the naive measurement?

Na food processing facility, a spherical container of inner radius r1 5 40 cm, outer radius r2 5 41 cm, and ther- mal conductivity k 5 1.5 w/m · k is used to store hot water and to keep it at 100°c at all times. to accomplish this, the outer surface of the container is wrapped with a 800-w electric strip heater and then insulated. the temperature of the inner surface of the container is observed to be nearly 120°c at all times. as- suming 10 percent of the heat generated in the heater is lost through the insulation, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the container, (b) obtain a relation for the variation of temperature in the container material by solving the differential equation, and (c) evaluate the outer surface tempera- ture of the container. also determine how much water at 100°c this tank can supply steadily if the cold water enters at 20°c.

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.

Which of the following is the phase that results when the moon is on the opposite side of the earth from the sun? a. quarter moon b. crescent moon c. new moon d. full moon