Seyfert galaxies are the only type that produces gravitational lensing
Indicate whether the statement is true or false
FALSE
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The type of adhesive that cures by the exclusion of oxygen is called ___________.
Fill in the blank(s) with the appropriate word(s).
Lubricating oil is cooled in a tubular heat exchanger to maintain its viscosity and effectiveness in the journal bearings used in a large steam turbine of an electric power plant. Oil flows at the rate of 0.1 kg/s inside a 12.5-mm-diameter circular tube, which is maintained at a uniform surface temperature of 25°C, and the oil is cooled from 80°C to 40°C. Calculate the length of tube required for this heat exchanger, the total heat flux dissipated from its surface in the cooling process, and the pressure drop across the tube length.
GIVEN
• Lubricating oil cooled in tubular heat exchanger.
• Oil flow rate, m = 0.1kg/s.
• Oil inlet temperature, Tb,in = 80°C.
• Oil outlet temperature Tb,out=400C
• Inner or inside diameter of pipe in which oil flows, D = 12.5 mm = 0.0125 m.
• Temperature of pipe surfaceTs = 25°C.
FIND
• Length of tube required for heat exchanger
• Total heat flux dissipated from its surface in cooling process.
• Pressure drop across the tube length.
ASSUMPTIONS
• The temperature of wall is constant and uniform across the length of pipe.
• The thermal resistance of the pipe is negligible, and hence the inside surface temperature of the pipe is Tw = Ts, this represents a uniform pipe surface temperature condition.
SKETCH
PROPERTIES AND CONSTANTS
for unused engine oil at Tb= 60°C
Density, ? = 864.0 kg/m3
Thermal conductivity, k = 0.140 W/(m K)
Absolute viscosity, ?b = 72.5 × 10–3 (Ns)/m2
Prandtl number, Pr = 1050 Specific heat, cp = 2047 J/(kg K)
At the pipe surface temperature of 25°C, the absolute viscosity ?s = 652 × 10–3 (Ns)/m2
What is the magnitude of the magnetic force on a charged particle (Q = 5.0 ?C) moving with a speed of 80 km/s in the positive x direction at a point where Bx = 5.0 T, By = ?4.0 T, and Bz = 3.0 T?
A. 2.8 N B. 1.6 N C. 1.2 N D. 2.0 N E. 0.4 N
Magnetic fields are produced by
a. constant electric currents. b. electric currents that vary sinusoidally with time. c. time-varying electric fields. d. all of the above. e. only (a) and (b) above.