A concrete wall of a cold storage room measures 3.0 m high, 5.0 m wide, and 20 cm thick. The inside wall is to be covered by a layer of wood in order to reduce the rate of thermal energy flow through the wall by 90 percent
The inner surface of the wooden wall is maintained at -10°C and the outer surface of the concrete wall is at 20°C. The thermal conductivities of concrete and wood are 0.80 W/m ? K (concrete) and 0.040 W/m ? K (wood). What is the temperature difference across the layer of wood?
A) 24 C°
B) 25 C°
C) 26 C°
D) 27 C°
E) 28 C°
D
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If the area of the plates of a parallel plate capacitor is tripled and the plate separation is halved, by what factor does the capacitance change?
A. it triples B. it doubles C. it increases by a factor of 6 D. it increases 1.5 times E. it decreases to 2/3 the original
Graphical Interpretation of Work: The net force that an animal exerts on a large piece of fruit it has found is observed and is shown in the graph in the figure. If the force is parallel to the motion of the fruit, how much work did the animal do during the encounter?
A. 12.5 J B. 50 J C. 25 J D. 22 J E. 0 J
The work done by the gas is zero during an
A) isothermal expansion. B) isobaric expansion. C) adiabatic expansion. D) isometric process.
When a switch is closed, completing an LR series circuit, the time needed for the current to reach three-quarters its maximum value is ____ time constants
a. 0.500 b. 0.693 c. 0.725 d. 1.33 e. 1.39