The _______________ of a radioactive substance is the time it takes for half of the parent isotope atoms to decay into daughter isotope atoms
Fill in the blank(s) with correct word
half-life
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Parallax measurements of the distances to the nearest stars use ________ as a baseline.
A. Earth's orbit B. Earth-Moon distance C. Earth's diameter D. about the length of a football field
Which of the following is not expected for a "hot Jupiter" that orbits 0.05 AU from its star?
A) cloudtop temperatures over 1000 K B) intense volcanism C) clouds made of rock dust D) density similar to or lower than Jupiter's
A charge Q is uniformly distributed along the x axis from x = a to x = b. If Q = 45 nC, a = ?3.0 m, and b = 2.0 m, what is the electric potential (relative to zero at infinity) at the point, x = 8.0 m, on the x axis?
A. 71 V B. 60 V C. 49 V D. 82 V E. 150 V
A thermocouple (0.8-mm-OD wire) used to measure the temperature of quiescent gas in a furnace gives a reading of 165°C. It is known, however, that the rate of radiant heat flow per meter length from the hotter furnace walls to the thermocouple wire is 1.1 W/m and the convective heat transfer coefficient between the wire and the gas is 6.8 W/(m2K). With this information, estimate the true gas temperature. State your assumptions and indicate the equations used.
GIVEN
• Thermocouple (0.8 mm OD wire) in a furnace
• Thermocouple reading (Tp) = 165°C
• Radiant heat transfer to the wire (qr/L) = 1.1 W/m
• Heat transfer coefficient ( ch ) = 6.8 W/(m2 K)
FIND
• Estimate the true gas temperature (TG)
ASSUMPTIONS
• The system is in equilibrium
• Conduction along the thermocouple is negligible
• Conduction between the thermocouple and the furnace wall is negligible
SKETCH
