Q: A hot dog can be considered to be a 12-cm
A hot dog can be considered to be a 12-cm-long cylinder whose diameter is 2 cm and whose properties are ρ = 980 kg/m3, cp = 3.9 kJ/kg⋅K, k = 0.76 W/m⋅K, and α = 2 × 10−7 m2/s. A hot dog initially at 5...
See AnswerQ: A two-layer wall is made of two metal plates,
A two-layer wall is made of two metal plates, with surface roughness of about 25 μm, pressed together at an average pressure of 10 MPa. The first layer is a stainless steel plate with a thickness of 5...
See AnswerQ: Consider the engine block of a car made of cast iron (
Consider the engine block of a car made of cast iron (k = 52 W/m⋅K and α = 1.7 × 10−5 m2/s). The engine can be considered to be a rectangular block whose sides are 80 cm, 40 cm, and 40 cm. The engine...
See AnswerQ: At a certain location, wind is blowing steadily at 7 m
At a certain location, wind is blowing steadily at 7 m/s. Determine the mechanical energy of air per unit mass and the power generation potential of a wind turbine with 80-m-diameter blades at that l...
See AnswerQ: An aluminum plate 25 mm thick (k = 235 W/
An aluminum plate 25 mm thick (k = 235 W/mâ‹…K) is attached to a copper plate with thickness of 10 mm. The copper plate is heated electrically to dissipate a uniform heat flux of 5300...
See AnswerQ: Obtain relations for the characteristic lengths of a large plane wall of
Obtain relations for the characteristic lengths of a large plane wall of thickness 2L, a very long cylinder of radius ro, and a sphere of radius ro.
See AnswerQ: An aluminum plate and a stainless steel plate are pressed against each
An aluminum plate and a stainless steel plate are pressed against each other at an average pressure of 20 MPa. Both plates have a surface roughness of 2 μm. Determine the impact on the temperature dro...
See AnswerQ: Obtain a relation for the time required for a lumped system to
Obtain a relation for the time required for a lumped system to reach the average temperature 1/2 (Ti + T∞), where Ti is the initial temperature and T∞ is the temperature of the environment.
See AnswerQ: Consider steady heat transfer through the wall of a room in winter
Consider steady heat transfer through the wall of a room in winter. The convection heat transfer coefficient at the outer surface of the wall is three times that of the inner surface as a result of th...
See AnswerQ: A brick of 203 × 102 × 57 mm in dimension is
A brick of 203 × 102 × 57 mm in dimension is being burned in a kiln to 1100°C and then allowed to cool in a room with ambient air temperature of 30°C and convection heat transfer coefficient of 5 W/m2...
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