What is the limiting angle of resolution for the eye if the pupil diameter of the eye is 4.0 mm, a wavelength of light of 600 nm and index of refraction for the eye equal to 1.34?
A)
4.2 × 10-4 rad
B)
2.1 × 10-4 rad
C)
1.4 × 10-4 rad
D)
1.1 × 10-4 rad
E)
2.6 × 10-4 rad
C
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What is the mass of a ball moving at 4 m/s with a momentum of 48 kg?m/s?
A) 4 kg B) 12 kg C) 48 kg D) 192 kg E) none of the above
If an AC circuit consists of a 220 mH inductor in series with a 75 k 
resistor and an AC generator with rms voltage of 12 V. At what frequency will the rms voltage drop across the resistor be equal to that across the inductor?
A. 114 kHz B. 5.5 kHz C. 875 Hz D. 18 kHz
In a manufacturing process, a fluid is transported through a cellar maintained at a temperature of 300 K. The fluid is contained in a pipe having an external diameter of 0.4 m and whose surface has an emissivity of 0.5. To reduce heat losses, the pipe is surrounded by a thin shielding pipe having an ID of 0.5 m and an emissivity of 0.3. The space between the two pipes is effectively evacuated to minimize heat losses and the inside pipe is at a temperature of 550 K. (a) Estimate the heat loss from the liquid per meter length, (b) If the fluid inside the pipe is an oil flowing at a velocity of 1 m/s, calculate the length of pipe for a temperature drop of 1 K.
GIVEN
- Fluid in concentric pipes, with the space between the pipes evacuated, running through a cellar space
- Cellar temperature (T?) = 300 K
- External diameter of inner pipe (D1) = 0.4 m
- Emissivity of outer pipe surface (?1) = 0.5
- Inside diameter of outer pipe (D2) = 0.5 m
- Emissivity of inner pipe (?2) = 0.3
- Inside pipe temperature (T1) = 550 K
FIND
(a) The heat loss from the liquid per meter length (q/L)
(b) The length of pipe for a temperature drop of 1 K if the fluid is oil flowing at a velocity (V) =1 m/s
ASSUMPTIONS
- Steady state
- Convection between the pipes is negligible
- The thermal resistance of the pipe walls is negligible
- The thickness of the outer pipe wall is negligible (Inside surface area = Outside surface area)
- Area of the cellar is large compared to the pipe so that cellar behaves as a blackbody enclosure at T?
- Oil has the thermal properties of unused engine oil
- The temperature of the inner pipe is constant
SKETCH
PROPERTIES AND CONSTANTS
the Stephan-Boltzmann constant
for unused engine oil at 550 K
Density (p) = 742 kg/m3
Specific heat (c) 2998 J/(kg K)
Cold damp weather along the eastern coast of the United States is most likely caused by a
A) continental tropical air mass. B) continental polar air mass. C) maritime tropical air mass. D) maritime polar air mass.