During a solar eclipse, the umbra moves across Earth's surface generally from
a. east to west.
b. west to east.
c. south to north.
d. north to south.
b
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To transmit four times as much energy per unit time along a string, you can
a. double the frequency. b. double the amplitude. c. increase the tension by a factor of 16. d. do any one of the above. e. do only (a) or (b) above.
Graphical Addition: Consider two vectors 
and 
shown in the figure. The difference 
-
is best illustrated by
A. choice (a) B. choice (b) C. choice (c) D. choice (d)
A mosquito flying at 3 m/s encounters a 3-m/s breeze blowing in the opposite direction, which gives it a resulting speed over the ground of
A) 0 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s.
A fluid flows at 5 m/s over a wide, flat plate 15-cm-long. For each of the following list, calculate the Reynolds number at the downstream end of the plate. Indicate weather the flow at that point is laminar, transition, or turbulent. Assume all fluids are at 40°C.
(a) Air
(b) CO2
(c) Water
(d) Engine Oil
GIVEN
A fluid flows over a flat plate
Fluid velocity (U?) = 5 m/s
Length of plate (L) = 15 cm = 0.15 m
Fluid temperature = 40°C
FIND
The Reynolds number at the downstream end of the plate (ReL) for
(a) Air
(b) CO2
(c) Water
(d) Engine Oil
Indicate if the flow is laminar, transitional, or turbulent
ASSUMPTIONS
Steady state
SKETCH
PROPERTIES AND CONSTANTS
