At the end of the Kelvin-Helmholtz contraction a star is hundreds of times brighter than it will be as a main sequence star
Indicate whether the statement is true or false
TRUE
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In a single-pass counterflow heat exchanger, 1.25 kg/s of water enter at 15°C and cools 2.5 kg/s of an oil having a specific heat of 2093 J/(kg K) from 95°C to 65°C. If the overall heat transfer coefficient is 280 W/(m2 K), determine the surface area required.
GIVEN
• Water cooling oil in a single-pass counterflow heat exchanger
• Water flow rate ( m w)= 1.25 kg/s
• Oil flow rate ( m o)= 2.5 kg/s
• Oil specific heat (cpo) = 2093 J/(kg K)
• Water inlet temperature (Tw, in) = 15°C
• Oil temperature
? To, in = 95°C
? To, out = 65°C
• Overall heat transfer coefficient (U) = 280 W/(m2 K)
FIND
• The surface area (A) required
SKETCH
PROPERTIES AND CONSTANTS
the specific heat of water (cpw) = 4187 J/(kg K)
1.000 L of water at 20.00°C will occupy what volume if it is heated to 80.00°C? Water has a volume expansion coefficient of 210 × 10-6/°C. (Express your answer to 4 significant figures.)
A) 1.600 L B) 1.326 L C) 1.013 L D) 0.9870 L E) 0.9987 L
If a = 3.0 mm, b = 4.0 mm, Q1 = 60 nC, Q2 = 80 nC, and q = 32 nC in the figure, what is the magnitude of the electric force on q?
A. 1.6 N B. 1.3 N C. 1.9 N D. 2.2 N E. 0.040 N
If 25 kg of ice at 0°C is combined with 4 kg of steam at 100°C, what will be the final equilibrium temperature (in °C) of the system?
a. 40 b. 20 c. 60 d. 100 e. 8