What special type of information is yielded only by eclipsing binary stars?
What will be an ideal response?
The analysis of the light curve of eclipsing binaries allows us to measure their sizes. As most are spectroscopic binaries as well, we can use their speeds and durations of various stages of the eclipse to directly measure their diameters. Basically, the longer the eclipse takes, the bigger the star is.
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A proton with mass 1.67 × 10^?27 kg moves in an accelerator with a speed of 0.780c. What is its total energy? (c = 3.00 × 10^8 m/s)
a. 1.50E–10 J b. 3.90E–10 J c. 2.40E–10 J d. 7.51E–19 J e. 1.28E–18 J
In space-based systems, such as the International Space Station, for example, highly efficient cooling systems are deployed that involve force convection boiling. In a laboratory experiment to develop one such system, a test liquid, which has the physical properties given, flows inside a vertical tube of 1.905 cm (or 0.75 in) inner diameter with a mass flux (or mass velocity) of 680 kg/(m2s). Determine the heat transfer coefficient at a point along the length of the tube at which the quality is 0.3. The wall temperature at this location was measured to be 1800C.
GIVEN
? 1.905 cm vertical tube with flowing, boiling water inside
? Test liquid with properties given above
? Mass flux (G)= 680 kg/(m2s)
FIND
(a) Heat transfer coefficient at a point along the length of the tube at which the quality is 0.3
ASSUMPTIONS
? The method of Chen is applicable
? Prandtl number of the fluid is Prl=1.0
PROPERTIES AND CONSTANTS
A steel pipe (E 5 190 GPa, ? 5 14 3 1026/°C, d2 5 82 mm, and d1 5 70 mm) of length L 5 4.25 m hangs from a rigid surface and is subjected to a temperature increase ¢T 5 50 °C. The column is fixed at the top and has a small gap at the bottom. To avoid buckling, the mini-mum clearance at the bottom should be approximately:
(A) 2.55 mm
(B) 3.24 mm
(C) 4.17 mm
(D) 5.23 mm
The amplitude of a 3.00-kg object in simple harmonic motion is 6.00 m. The maximum acceleration of the object is 5.00 m/s2. What is the period of simple harmonic motion?
A) 6.88 s B) 1.20 s C) 0.278 s D) 0.833 s E) 7.54 s