In: Physics
1. A 100 g ice cube at -10?C is placed in an aluminum cup whose initial temperature is 70?C. The system comes to an equilibrium temperature of 20?C. What is the mass of the cup in kg.
2.Radiation from the head is a major source of heat loss from the human body. Model a head as a 20-cm-diameter, 20-cm-tall cylinder with a flat top.If the body's surface temperature is 36 ?C , what is the net rate of heat loss in units W on a chilly 6 ?C day? All skin, regardless of color, is effectively black in the infrared where the radiation occurs, so use an emissivity of 0.97.
1)
Heat lost by aluminium cup = Heat gained by ice cube
Mass of the aluminium cup is
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2)
Rate of heat loss is
Given that, Radius of cylinder
Height of the cylinder
Temperature of body surface
Temperature of surroundings
Emissivity
Total area of cylinder (head ) where the heat is lost = Area of flat top+ Area of lateral surface
Heat loss from the head is