Soaring birds and glider pilots can remain aloft for hours without expending power, due to
A) conduction.
B) convection.
C) radiation.
D) all of the above
Answer: B
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Gaps in the asteroid belt (often called Kirkwood gaps) are caused by ________
A) tidal forces from Jupiter B) tidal forces from the Sun C) the competing gravitational tugs of Mars and Jupiter D) orbital resonances with Jupiter
A long cylindrical rod, 8 cm in diameter, is initially at a uniform temperature of 20°C. At time t = 0, the rod is exposed to an ambient temperature of 400°C through a heat transfer coefficient of 20 W/(m2 K). The thermal conductivity of the rod is 0.8 W/(mK) and the thermal diffusivity is 3 × 10–6 m2/s. Determine how much time will be required for the temperature change at the centerline of the rod to reach 93.68% of its maximum value. Use an explicit difference equation and compare your numerical results with a chart solution.
GIVEN • Cylindrical rod suddenly exposed to increased ambient temperature FIND (a) Time required for the centerline temperature change to reach 93.68% of its maximum value
The fundamental frequency of HF is 8.72 × 10^13 Hz. The energy associated with a transition from the 10th to the 9th vibrational quantum number (in eV) is
a. 3.61 b. 0.361 c. 0.060 5 d. 0.605 e. 0.182
An n-type semiconductor is produced in polyacetylene by doping with:
(a) Arsenic (b) Phosphorus (c) Fluorine (d) Lithium