Q 84

When 50 g of a certain material at 100°C is mixed with 100 g of water at 0°C,the final temperature is 40°C.What is the specific heat of the material? The specific heat of water is 1.00 kcal/kg ∙ °C.
A)0.33 kcal/kg ∙ °C
B)0.75 kcal/kg ∙ °C
C)1.3 kcal/kg ∙ °C
D)7.5 kcal/kg ∙°C

Q 85

A heat-conducting rod,0.90 m long and wrapped in insulation,is made of an aluminum section that is 0.20 m long and a copper section that is
Long.Both sections have a cross-sectional area of
The aluminum end and the copper end are maintained at temperatures of
And
Respectively.The thermal conductivities of aluminum and copper are 205 W/m ∙ K (aluminum)and 385 W/m ∙ K (copper).What is the temperature of the aluminum-copper junction in the rod with steady state heat flow?
A)100°C
B)93°C
C)86°C
D)80°C
E)74°C

Q 86

A heat conducting rod,1.60 m long and wrapped in insulation,is made of an aluminum section that is 0.90 m long and a copper section that is
Long.Both sections have a cross-sectional area of
The aluminum end and the copper end are maintained at temperatures of
And
Respectively.The thermal conductivities of aluminum and copper are 205 W/m ∙ K (aluminum)and 385 W/m ∙ K (copper).At what rate is heat conducted in the rod under steady state conditions?
A)9.0 W
B)7.9 W
C)10 W
D)11 W
E)12 W