A car is making a 12-mile trip. It travels the first 8.0 miles at 30 miles per hour and the last 4.0 miles at 60 miles per hour. What is the car's average speed for the entire trip?
A) 36 mph
B) 40 mph
C) 44 mph
D) 48 mph
E) 52 mph
A
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Determine ? when I = 0.50 A and R = 12 ?.
A. 12 V B. 24 V C. 30 V D. 15 V E. 6.0 V
In a nuclear power plant, the reactor produces 500°C steam that is used to power the steam turbines which generate 1500 MW of electrical power. The cooling tower eliminates the waste heat at 50°C. If the efficiency of the plant were that of a Carnot engine, at what rate would waste heat be vented to the atmosphere?
Force on a Moving Charge: If a calculated quantity has units of T ? m/A, that quantity could be
A. an electric field. B. an electric potential. C. ?0. D. a magnetic field. E. a magnetic torque.
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