During each cycle of operation a refrigerator absorbs 55.0 cal from the freezer compartment and expels 88.0 cal to the room. If one cycle occurs every 10 s, how many minutes will it take to freeze 575 g of water, initially at 0°C? (Lv = 80 cal/g)
a. 69.7 min
b. 1 390 min
c. 139 min
d. 87.1 min
e. 836 min
c
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The interior wall of a large commercial, walk-in type meat freezer is covered under normal operating conditions with a 2 cm thick layer of ice. One day, a power outage cuts electricity to the refrigeration system of the freezer. Estimate the time required to melt this layer of ice if it has mass density of 700 kg/m3 and latent heat of fusion of 334 kJ/kg. Consider the air temperature inside the freezer to be 200C with a heat transfer coefficient of 2 W/(m2 K) for convection from freezer surface to air, and clearly state the assumptions made in the calculations.
GIVEN
FIND
- Time required to melt the layer of ice
ASSUMPTIONS
- Steady state conditions prevail
- Radiative heat loss is negligible
The luminosity class is assigned to a star by studying the absorption lines in the spectrum of the star
a. True b. False Indicate whether the statement is true or false
A vector lies in the x-y plane. For what orientations will both components be negative?
1.The vector lies between 180° and 270° from the x-axis. 2.The vector lies between 0° and 90° from the x-axis. 3.The vector lies between 90° and 180° from the x-axis. 4.None. Just like for vector magnitudes, components are always positive.
Light from the sun is illuminating a fish in the water. The sun is at 45° relative to a perpendicular to the water surface. What is the angle of the suns rays in the water relative to a perpendicular to the water surface?
What will be an ideal response?