When 1.0-µC point charge is 15 m from a second point charge, the force each one experiences a force of 1.0 µN. What is the magnitude of the second charge? (k = 1/4??0 = 9.0 × 109 N ? m2/C2)
A) 25 C
B) 1.0 C
C) 10 nC
D) 0.025 C
E) 25 nC
E
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In a certain region of space, the electric field is zero. From this fact, what can you conclude about the electric potential in this region?
1.It is zero. 2.It is constant. 3.It is positive. 4.It is negative. 5.None of these answers is necessarily true.
400 cm3 of mercury at 0°C will expand to what volume at 50°C? Mercury has a volume expansion coefficient of 180 × 10-6/C°
A) 450 cm3 B) 422.8 cm3 C) 409.7 cm3 D) 403.6 cm3 E) 401.8 cm3
What property primarily determines the effect of temperature on the solubility of gas molecules?
A) the kinetic energy of the gas B) the polarity of the gas C) the molecular weight of the gas D) the ionic strength of the gas E) the dipole strength of the solvent
Steam at 1 atm and 100°C is flowing across a 5-cm-OD tube at a velocity of 6 m/s. Estimate the Nusselt number, the heat transfer coefficient, and the rate of heat transfer per meter length of pipe if the pipe is at 200°C.
GIVEN
• Steam flowing across a tube
• Steam pressure = 1 atm
• Steam bulk temperature (Tb) = 100°C
• Tube outside diameter (D) = 5 cm = 0.05 m
• Steam velocity (V) = 6 m/s
• Pipe surface temperature (Ts) 200°C
FIND
(a) The Nusselt number Nu D (b) The heat transfer coefficient h c(c) The rate of heat transfer per unit length (q/L)
ASSUMPTIONS
• Steady state
SKETCH
PROPERTIES AND CONSTANTS
Thermal conductivity (k) = 0.0249 W/(m K) Kinematic viscosity (?) = 20.2 × 10–6 m2/s Prandtl number (Pr) = 0.987 At the tube surface temperature of 200°C, the Prandtl number of the steam (Prs) = 1.00