How do disk stars orbit the center of the galaxy?
A) They all orbit in roughly the same plane and in the same direction.
B) They have orbits randomly inclined and in different directions relative to the galactic center.
C) They follow spiral paths along the spiral arms.
D) They follow orbits that move up and down through the disk, typically taking them about 50,000 light-years above and below the disk on each orbit.
A
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The horizontal cross section of an industrial chimney is shown in the accompanying sketch. Flue gases maintain the interior surface of the chimney at 300°C and the outside is exposed to ambient temperature of 0°C through a heat transfer coefficient of 5 W/(m2 K). The thermal conductivity of the chimney is k = 0.5 W/(mK). For a grid spacing of 0.2 m, determine the temperature distribution in the chimney and the rate of heat loss from the flue gases per unit length of the chimney.
GIVEN
Chimney with hot flue gases inside, ambient temperature outside
FIND
(a) Temperature distribution in the chimney
(b) Rate of heat loss from the flue gases per unit length
ASSUMPTIONS
Steady state conditions
Neglect radiation heat transfer
SKETCH
You leave on a 549-mi trip in order to attend a meeting that will start 10.8 h after you begin your trip. Along the way you plan to stop for dinner
If the fastest you can safely drive is 65 mi/h, what is the longest time you can spend over dinner and still arrive just in time for the meeting? A) 2.4 h B) 2.6 h C) 1.9 h D) You can't stop at all.
Kepler's first law of planetary motion is known as the law of ______________ paths
Fill in the blank(s) with correct word
Beats: Two strings both vibrate at exactly 819 Hz. The tension in one of them is then increased slightly. As a result, six beats per second are heard when both strings vibrate. What is the new frequency of the string that was tightened?
A. 825 Hz B. 813 Hz C. 822 Hz D. 816 Hz