What causes the outward pressure that balances the inward pull of gravity in a star?
a. the outward flow of energy
b. the opacity of the gas
c. the temperature of the gas
d. the density of the gas
e. the temperature and the density of the gas
a
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Stars in the upper right part of the Hertzsprung-Russell diagram are always ____ when compared to stars near the middle of the diagram
a. cooler b. brighter as seen from Earth c. larger d. smaller e. more massive
Velocity: What must be your average speed in order to travel 350 km in 5.15 h?
A. 66.0 km/h B. 67.0 km/h C. 68.0 km/h D. 69.0 km/h
A physical barrier to listening might include
a. thinking about what to have for lunch b. lack of focus c. being biased against the speaker d. loud music
When two organ pipes each closed at one end sound a perfect fifth, such as two notes with fundamental frequencies at 440 Hz and 660 Hz, both pipes produce overtones. Which choice below correctly describes overtones present in both pipes?
a. 440, 880 and 1 320 Hz. b. 660, 1 320 and 1 980 Hz. c. 880, 1 320 and 1 760 Hz. d. 1 320, 2 640 and 3 960 Hz. e. They have no overtones in common.