A ray of light hits a flat surface at an angle ? and is diffusely reflected. At what angle is it reflected?
1. ?
2. 2?
3. –?
4. unknown
4
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_________ are electromagnetic radiation with wavelengths typically from 0.1 nm to 1 nm.
Fill in the blank(s) with the appropriate word(s).
Water enters a small copper tube, with an inner diameter of 2.5 cm, at the rate of 0.025 kg/s and a temperature of 15°C. Steam is condensing on the outer surface of the tube at atmospheric pressure so that tube-surface temperature is uniformly at 100°C. If the tube length is 5 meters, determine (a) the outlet temperature, and (b) the average convection heat transfer coefficient between the water and the pipe.
GIVEN • Diameter of copper tube (Di)= 2.5 cm = 0.025 m • Cooling water inlet temperature (Tin)= 200C • Cooling water flow rate ( m• )=0.025 kg/s • Tube length (L)= 5 m • Surface temperature(Ts)=1000C FIND (a) Outlet temperature (b) Average convection heat transfer coefficient between water and pipe. PROPERTIES AND CONSTANTS for Water at 35°C: (guess bulk temperature) Density (?) = 994.1 kg/m3 Specific heat (cp) = 4175 J/(kg K) Thermal conductivity (k) = 0.624 W/(m K) A bsolute viscosity (?) = 719.8 × 10–6 (Ns)/m2 Prandtl Number (Pr) = 4.8
A star is crossing your meridian right now. When will it cross the meridian next?
A) very close to 23 hours, 56 minutes from now B) very close to 24 hours from now C) one year from now D) It depends on the star's position on the celestial sphere.
Sound interference with a pair of radio loudspeakers can be nicely demonstrated when the
A) radio signal is monaural for each. B) input and output of the speakers are reversed. C) speakers are brought face to face. D) all of the above E) none of the above