According to current theories, the universe appears to be made
A) of dark matter
B) of dark energy
C) mostly of ordinary matter in the form of stars and galaxies
D) of an equal mixture of dark matter and dark energy
B
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A meson is
A. a bound triplet of quarks. B. a bound triplet of antiquarks. C. a bound quark-antiquark pair. D. a bound system of four quarks and one antiquark.
Consider the problem described in Example 8.5. Show that the transient heating of the water in the pan, assuming the water to be well-mixed and thermally homogenous at any instant in time, can be expressed by the following:
where V is the volume of water in the pan and A is the area of the bottom surface of the
pan. Solve this equation (numerically or otherwise) to determine the time required to
heat the water to (a) 50°C and (b) 80°C. Also, determine the total heat transfer to the
water in the pan in each case.
GIVEN
? A covered pan kept in stove-top burner
? Depth of pan (L)= 8 cm
? Pan bottom surface temperature (Ts) = 100°C
? Initial water temperature at top (T?) = 20°C
? Diameter of the pan (D) = 15 cm
FIND
? Show the expression for heat flow through convection to pan
? Time required and total heat transfer to water while heating the water to 500C and 800C
ASSUMPTIONS
? Radiation heat transfer is negligible
SKETCH
Refer to Example 8.5
PROPERTIES AND CONSTANTS
From Appendix 2, Table 28, for dry air at the mean temperature of 60°C
A 6.0-m wire with a mass of 50 g, is under tension. A transverse wave, for which the frequency is 810 Hz, the wavelength is 0.40 m, and the amplitude is 4.0 mm, is propagating on the wire
The time for a crest of this wave to travel the length of the wire is closest to A) 19 ms. B) 16 ms. C) 21 ms. D) 23 ms. E) 25 ms.
Project a cannonball from atop Newton's hypothetical mountain at 8 km/s and it orbits Earth. Project it at 9 km/s and the shape of the orbit is
A) a somewhat larger circle. B) a wide parabola. C) an ellipse.