Astronomers estimate that the age of the Solar System is about ________ years.
A. 4.6 billion
B. 4.6 million
C. 4.6 trillion
D. 13.7 billion
Answer: A
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What is the binding energy per nucleon for 12C?
A. 137 MeV B. 104 MeV C. 92.2 MeV D. 46.1 MeV E. 7.68 MeV
Reconsider the problem of cooling of a rotating rod (shaft) by natural convection described in Example 8.6. Determine the shaft rotation at which the heat transfer contribution due to the rotation convection is about the same as that due to natural convection, and calculate the total heat transfer rate at this condition. Also, graph the variation of q, as well as its two components (qr and qnc) with shaft rpm ranging from 3 rpm to 15 rpm, and comment upon the results.
GIVEN
? Cooling of rotational shaft by natural convection
? Rod diameter (D) = 20 cm = 0.2 m
? Air temperature (T?) = 20°C
? Temperature of rotating rod (Tb) = 1000°C
FIND
? Shaft rotation at which heat transfer contribution due to rotational convection is same as that due
to natural convection.
? Total heat transfer rate at this condition.
? Graph of variation of q and qr and qnc with shaft rpm.
ASSUMPTIONS
? Radiation is negligible
? The shaft is horizontal
PROPERTIES AND CONSTANTS
Standing Sound Waves: A violin with string length 32 cm and string density 1.5 g/cm resonates in its fundamental with the first overtone of a 2.0-m organ pipe with one end closed and one end open. What is the tension in the string if the speed of sound in air is 344 m/s?
A. 1000 N B. 110 N C. 450 N D. 4100 N E. 56 N
A 100-V DC signal is applied to a series circuit composed of four equal resistors 10 ? each. What is the voltage across each resistor?
A) 10 V B) 15 V C) 20 V D) 25 V E) 50 V