After striking a concave mirror, a paraxial beam of light passes through the mirror's focal point
Indicate whether the statement is true or false
TRUE
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Diamond has a notably high thermal conductivity because of its strong chemical _____________.
Fill in the blank(s) with the appropriate word(s).
As described by Kepler's second law, an object in an elliptical orbit reaches its highest velocity when it is as at ____
a. lowest; perigree b. highest; apogee c. highest; perigree d. lowest; apogee e. escape velocity; perigree
Which of the following quantities has units of a displacement? (There could be more than one correct choice.)
A) 32 ft/s2 vertically downward B) 40 km southwest C) 9.8 m/s2 D) -120 m/s E) 186,000 mi
The average Reynolds number for air passing in turbulent flow over a 2-m-long flat plate is 2.4 x 106. Under these conditions, the average Nusselt number was found to be equal to 4150. Determine the average heat transfer coefficient for an oil having thermal properties similar to those in Appendix 2, Table 18 at 30°C at the same Reynolds number and flowing over the same plate.
GIVEN
Turbulent flow of air over a flat plate
Average Reynolds number (ReL) = 2.4 x 106
Plate length (L) = 2 m
Average Nusselt number (Nu) = 4150
FIND
Average heat transfer coefficient
ASSUMPTIONS
Steady state
Fully developed turbulent flow
Transition from laminar to turbulent flow occurs at Rex = 5 x 105
SKETCH
PROPERTIES AND CONSTANTS
From Appendix 2, Table 18, for oil at 30°C
Thermal Conductivity (k) = 0.11 W/(m K)
Kinematic Viscosity (v) = 15.4 ? 10–6 m2/s
Thermal Diffusivity (a) = 707 ? 10–10 m2/s