Coffee beans are roasted by floating them with a column of hot air at 250°c. if the beans start at 22°c and are done when they reach 200°c, how long does this process takewith average convection of h =20 w/m2°c? assume the coffee beans have typical volume and surface areas of 44 mm3 and 66 mm2 respectively, a conductivity of 0.184 w/m°c, specific heat of 2.564 kj/kg °c and a density of 552 kg/m3. assume that the beans are relatively dry at the start of this process and evaporative losses can be neglected.

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

Pls pls pls pls ! describe, in your own words, how you found the epicenter of the earthquake.

A1000-kg weather rocket is launched straight up. the rocket motor provides a constant acceleration for 16-s, then the motor stops. the rocket altitude 20-s after launch is 510-m. you can ignore any effects of air resistance. a. what was the rocket’s acceleration during the first 16-s? b. what is the rocket’s speed as it passes through a cloud 5100-m above the ground?