Atomic Nucleus: The atomic number and mass number for calcium-39 are 20 and 39, respectively. How many neutrons are in one atom?
A. 1
B. 19
C. 20
D. 39
E. 59
Answer: B
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What is simple harmonic motion?
A metal-clad electrical heating element of cylindrical shape, as shown in the sketch below, is immersed in water at atmospheric pressure. The element is a 5-cm-OD, and heat generation produces a surface temperature of 300°C. Estimate the heat flux under steady state conditions and the rate of heat generation per unit length.
GIVEN
? Cylindrical, electrical heating element
? Heat generation produces a 300°C surface temperature
FIND
(a) Heat flux
(b) Rate of heat generation
ASSUMPTIONS
? The system operates at atmospheric pressure
? The heater surface is black
SKETCH
PROPERTIES AND CONSTANTS
Inspection of the boiling curve in Figure (9.1) indicates that at 300°C surface temperature, the heating system must operate in the film boiling regime. Hence, a vapor layer covers the surface of the heater and it is appropriate to evaluate the physical properties at the mean film temperature of (100 + 300)/2 = 200°C.
From Appendix 2, Table 35
From Appendix 2, Table 13
The age of the Universe can be deduced from
A. Kepler's Third law. B. Hubble's law. C. Shapley's law. D. the Doppler shift law. E. the Inverse-square law.
Fissioning carbon would occur with
A) absorption of energy. B) release of energy. C) neither of these