The thickness of an aluminum foil is measured using 315-nm wavelength light in a Michelson interferometer that has its movable mirror mounted on a very finely threaded distance gauge (commonly called a "micrometer screw gauge" or often just a "micrometer"). There is a difference of 27 fringes in the observed interference pattern when the micrometer clamps down on the foil compared to when the micrometer is empty (clamped down on nothing). Calculate the thickness of the foil?

Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer. provide a plausible explanation for this situation (with supporting calculations) by considering a room whose air temperature is maintained at 20â°c throughout the year, while the walls of the room are nominally at 27â°c and 14â°c in the summer and winter, respectively. the exposed surface of a person in the room may be assumed to be at a temperature of 32â°c throughout the year and to have an emissivity of 0.90. the coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 w/m2 â‹…â‹… k. what is the ratio of the thermal resistance due to convection to the thermal resistance due to radiation in the summer? what is the ratio of thermal resistances in the winter

15. one purpose of the tread pattern on a tire is to a reduce tire wear. b. reduce traction c. allow water to flow away from the tire. d. look impressive.

Asolid round steel rod 6.25 mm in diameter and 375 mm long is rigidly bonded to the end of solid square brass rod 25 mm on a side and 300 mm long. the geometric axes of the bare are along the same line. an axial tensile force of 5.4 kn is applied at the extreme ends of the assembly. for steel e = 200 gpa and for brass e = 90 gpa. determine the total elongation for the assembly.