Why is ozone so crucial to the continued well-being of life on Earth?
What will be an ideal response?
Ozone (O3 ) absorbs ultraviolet photons from the Sun and prevents them from reaching the ground where these high-energy photons would harm biological life.
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Compute the average heat transfer coefficient hc for 10°C water flowing at 4 m/s in a long, 2.5-cm-ID pipe (surface temperature 40°C) by three different equations and compare your results. Also determine the pressure drop per meter length of pipe.
GIVEN
• Water flowing through a pipe
• Water temperature (Tb) = 10°C
• Water velocity (V) = 4 m/s
• Inside diameter of pipe (D) = 2.5 cm = 0.025 m
• Pipe surface temperature (Ts) = 40°C
FIND
(a) The average heat transfer coefficient ( h c) by 3 different equations.
(b) The pressure drop per meter length (?p/L)
ASSUMPTIONS
• Steady state
• Uniform and constant wall surface temperature
• Pipe wall is smooth
• Fully developed flow (L/D > 60)
SKETCH
PROPERTIES AND CONSTANTS
for water at 10°C
for water at 10°C
Density (?) = 999.7 kg/m3
Thermal conductivity (k) = 0.577 W/(m K)
Kinematic viscosity (?) = 1.300 × 10–6 m2/s
Prandtl number (Pr) = 9.5
Absolute viscosity (?b) = 1296 × 10–6 (Ns)/m2
At the surface temperature of 40°C ?s = 658 × 10–6 (Ns)/m2
Recall that an up quark (u) has a charge of +2/3 and a down quark (d) has a charge of ?1/3. Which of the following quark compositions describes a proton?
A) uud B) uuu C) udd D) uuudd
Which of the following types of interference will occur when the pulses in the figure above meet?
a. no interference b. constructive interference c. destructive interference d. total interference
Huge collections of stars in space containing anywhere form a few hundred million to more than a trillion stars are referred to as
A) island universes B) galaxy clusters C) star clusters D) galaxies