Apiece of wood with a density of 706 kg/m3 is tied with a string to the bottom of a water-filled flask. the wood is completely immersed. suppose the flask with the wood tied to the bottom is placed on a scale. at some point the string breaks and the wood rises to the surface where it floats.

part a

when the wood is floating, is the reading on the scale greater than, less than, or equal to its previous reading?

part b

choose the best explanation from among the following:

when the block is floating it no longer pulls upward on the flask; therefore, the reading on the scale increases.
the same mass is supported by the scale before and after the string breaks, and therefore the reading on the scale remains the same.

Which is not a characteristic of a heat pump? a. it is used in air conditioners. b. it uses a refrigerant. c. it requires no work. d. it reverses the normal flow of thermal energy.

The respiratory system removes oxygen and water from the body. select the best answer from the choices provided t f

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?