What is the expression for efficiency () in terms of the work W done by the system and the heat Q added to it?
a. = WQ
b. = Q/W
c. = Q + W
d. = Q + 273K
e. = W/Q
e
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A radio wave transmits 1.59 W/m2 average power per unit area. What is the peak value of the associated magnetic field? (?0 = 4? × 10^?7 T?m/A and c = 3.00 × 10^8 m/s)
a. 1.33E–14 T b. 3.46E+1 T c. 1.15E–7 T d. 7.28E–5 T e. 8.16E–8 T
John throws a rock down with speed 11 m/s from the top of a 25-m tower. If g = 9.8 m/s2 and air resistance is negligible, what is the rock's speed just as it hits the ground?
a. 19 m/s b. 25 m/s c. 610 m/s d. 22 m/s e. 12 m/s
In gas turbine recuperators, the exhaust gases are used to heat the incoming air and Cmin/Cmax is therefore approximately equal to unity. Show that for this case e = NTU/(1 + NTU) for counterflow and e = 1/2 (1 – e– 2NTU) for parallel flow.
GIVEN
• Gas turbine recuperator
• Cmin /Cmax ? 1
FIND Show that
(a) e = NTU/(1 + NTU) for counterflow
(b) e = 1/2 (1 – e– 2NTU) for parallel flow
SKETCH
What type of glacier is formed when a valley floor is covered with compressed glacial ice?
a. Continental glacier b. Stream glacier c. Valley glacier d. Cirque glacier