How much of the solar system's total mass is contained in the Sun?
A) about half
B) about 90%
C) about 95%
D) about 99.8%
E) exactly 100%
D) about 99.8%
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Water entering a shell-and-tube heat exchanger at 35°C is to be heated to 75°C by an oil. The oil enters at 110°C and leaves at 75°C. The heat exchanger is arranged for counterflow with the water making one shell pass and the oil two tube passes. If the water flow rate is 68 kg per minute and the overall heat transfer coefficient is estimated from Table 10.1 to be 320 W/(m2 K), calculate the required heat exchanger area.
GIVEN
• One shell pass, two tube passes counterflow heat exchanger with water in shell, oil in tube
• Water temperatures Tw,in = 35°C Tw,out = 75°C
• Oil temperatures To,in = 110°C Tw,out = 75°C
• Water flow rate m n= 68 kg/min = 1.133 kg/s
• Overall heat transfer coefficient (U) = 320 W/(m2 K)
FIND
• The required area (A)
SKETCH
PROPERTIES AND CONSTANTS
the specific heat of water at the average temperature of 55°C (cpw)= 4180 J/(kg K)
Which of the following telescopes is most suitable for observing cool gas clouds?
A. radio telescope B. visible-light telescope C. X-ray telescope D. All of these choices are correct. E. Cool gas clouds cannot be observed by telescopes.
In the inner part of the asteroid belt one is more likely to find silicate-rich asteroids, while the carbon-rich asteroids are more abundant in the outer parts of the Asteroid belt.
Answer the following statement true (T) or false (F)
The vector sum of three co-planar forces
a. must be zero. b. must be perpendicular to one of the three. c. must be parallel to one of the three. d. must be perpendicular to the plane. e. may have any direction in the plane.