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This print-out should have 7 questions.Multiple-choice questions may continue onthe next column or page – find all choicesbefore answering.

Serway CP 11 19001 10.0 points

A student drops two metallic objects into a20 g steel container holding 298 g of water at20!C. One object is a 415 g cube of copperthat is initially at 81!C, and the other is achunk of aluminum that is initially at 5!C.To the student’s surprise, the water reaches afinal temperature of 20!C, precisely where itstarted.What was the mass of the aluminum chunk?

Assume the specific heat of aluminum is900 J/kg ·! C and of copper 387 J/kg ·! C.

Serway CP 11 27002 10.0 points

A 20 g block of ice is cooled to !64!C. It isadded to 558 g of water in an 100 g coppercalorimeter at a temperature of 21!C.Find the final temperature. The specific

heat of copper is 387 J/kg ·!C and of ice is2090 J/kg ·!C . The latent heat of fusion ofwater is 3.33" 105 J/kg and its specific heatis 4186 J/kg ·!C .

Serway CP 11 48003 10.0 points

A 1.13 m2 solar collector collects radiationfrom the Sun and focuses it on 320 g of waterthat is initially at 22.1!C. The average in-tensity of radiation arriving from the Sun atEarth’s surface at this location is 558 W/m2,and we assume that this is collected with100% e!ciency.Find the time required for the collector to

raise the temperature of the water to 100!C.The heat capacity of water is 4186 J/kg ·! C .

Correct answer: 2.75818 min.

Serway CP 11 36004 10.0 points

A box with a total surface area of 1.52 m2 anda wall thickness of 2.37 cm is made of an insu-lating material. A 8.3 W electric heater insidethe box maintains the inside temperature at20.3!C above the outside temperature.Find the thermal conductivity of the insu-

lating material.

Heat Loss Through Glass005 10.0 points

A Thermopane window of area 8.9 m2 is con-structed of two layers of glass, each 2.7 mmthick separated by an air space of 5 mm.If the inside is at 12!C and the outside is

at !28!C, what is the heat loss through thewindow? The thermal conductivity of glass is0.8 W/m ·

! C and of air is 0.0234 W/m ·! C .

Skin Temperature006 10.0 points

A child has a temperature of 101!F .If her total skin area is 76 m2, find the

energy loss per second due to radiation, as-suming the emissivity is 1. Assume the roomtemperature is 70!F. The Stephan-Boltzmannconstant is 5.6696" 10"8 W/m2

·K4 .

Correct answer: 8241.37 W.

Skin Blackbody Emission007 10.0 points

The temperature of your skin is approxi-mately 35!C.What is the wavelength at which the peak

occurs in the radiation emitted from yourskin?