The second law of thermodynamics leads us to conclude that
A) the total energy of the universe is constant.
B) disorder in the universe is increasing with the passage of time.
C) it is theoretically possible to convert heat into work with 100% efficiency.
D) the average temperature of the universe is increasing with the passage of time.
B
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Uranus was discovered:
A) by Galileo. B) thousands of years ago. C) with a radio telescope. D) after examining perturbations in Neptune's orbit. E) less than 250 years ago.
_______________ is believed to be produced by supernova explosions
Fill in the blank(s) with correct word
A mercury bath at 60°C is to be heated by immersing cylindrical electric heating rods, each 20 cm tall and 2 cm in diameter. Calculate the maximum electric power rating of a typical rod if its maximum surface temperature is 140°C.
GIVEN
• Cylindrical heating rods in a mercury bath
• Mercury temperature (T?) = 60°C
• Rod diameter (D) = 2 cm = 0.02 m
• Rod height (L) = 20 cm = 0.2 m
• Maximum surface temperature (Ts) = 140°C
FIND
• The maximum electric power rating ( q e) of a rod
ASSUMPTIONS
• Steady state
• The rods are in a vertical position
SKETCH
PROPERTIES AND CONSTANTS
for mercury at the mean temperature of 100°C
Thermal conductivity (k) = 10.51 W/(m K) Kinematic viscosity (?) = 0.093 × 10–6 m2/s Prandtl number (Pr) = 0.0162 Also Density at 50°C (?50) = 13,506 kg/m3
Density at 15°C (?150) = 13,264 kg/m3 To find the thermal expansion coefficient (?),
A jet plane flying 600. m/s experiences an acceleration of 4.0 g when pulling out of the dive. What is the radius of curvature of the loop in which the plane is flying?
A) 1.2 km B) 5.8 km C) 0.64 km D) 9.2 km E) 7.0 km