You are conducting an experiment inside an elevator that can move in a vertical shaft. a load is hung vertically from the ceiling on a string. the tension in the string is measured to be exactly equal to the force due to gravity on the load. no other forces are acting on the load. which of the following statements about the elevator are correct? check all that apply. check all that apply. the elevator is an inertial frame of reference. the elevator is not an inertial frame of reference. the elevator may be at rest. the elevator may be moving at a constant velocity upward. the elevator may be moving at a constant velocity downward. the elevator may be accelerating. the elevator must be accelerating.

Clothing made of several thin layers of fabric with trapped air in between, often called ski clothing, is commonly used in cold climates because it is light, fashionable, and a very effective thermal insulator. so it is no surprise that such clothing has largely replaced thickand heavy old-fashioned coats. (a) consider a jacket made of five layers of 0.1-mm-thick synthetic fabric (k = 0.13 w/m·°c) with 1.5-mm-thick air space (k = 0.026 w/m·°c) between the layers. assuming the inner surface temperature of the jacket to be 28°c and the surface area to be 1.25 m2, determine the rate of heat loss through the jacket when the temperature of the outdoors is 0°c and the heat transfer coefficient at the outer surface is 25 w/m2·°c. (b) what would your response be if the jacket is made of a single layer of 0.5-mm-thick synthetic fabric? what should be the thickness of a wool fabric (k = 0.035 w/m·°c) if the person is to achieve the same level of thermal comfort wearing a thick wool coat instead of a five-layer ski jacket?