Why do higher-mass stars live shorter lives on the main sequence than lower-mass stars?
a. Higher-mass stars burn through their nuclear fuel faster.
b. Lower-mass stars don't get their energy from that same nuclear fusion source as higher-mass stars.
c. Higher-mass stars have less hydrogen fuel to burn.
d. Lower-mass stars spend a longer time evolving to the main sequence.
e. All of the other choices are false.
a
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When an earthquake occurs, no direct _______________ pass through the core to register on seismographs on the opposite side of Earth
Fill in the blank(s) with correct word
Jupiter's bright zones are cloud streams made of ________ ice crystals
A) ammonia B) hydrogen C) methane D) water E) helium
After a switch is thrown to remove the battery from a DC LR circuit, but the circuit is still left complete, the time constant represents
a. the time rate of change of the current in the circuit. b. the time rate of change of the induced emf in the circuit. c. the magnitude of the ratio of the current to the time rate of change of the current. d. all of the above. e. only (a) and (b) above.
A turbine blade 6.3-cm-long, with cross-sectional area A = 4.6 x 10–4 m2 and perimeter P = 0.12 m, is made of stainless steel (k = 18 W/(m K). The temperature of the root, Ts, is 482°C. The blade is exposed to a hot gas at 871°C, and the heat transfer coefficient h? is 454 W/(m2 K). Determine the temperature of the blade tip and the rate of heat flow at the root of the blade. Assume that the tip is insulated.
GIVEN
FIND
ASSUMPTIONS
Steady state conditions prevail
The thermal conductivity is uniform
The tip is insulated
The cross-section of the blade is uniform
One dimensional conduction
SKETCH
