Star A and Star B have same temperatures, but Star A is more luminous than Star B. Based on this information, which of the following must be the case?
A. Star A is larger than Star B.
B. Star A is smaller than Star B.
C. Star A and Star B have same size.
D. Star A is more massive than Star B.
Answer: A
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The specific elastic modulus of the magnesium alloy AZ31B is equal to _________GPa.
Fill in the blank(s) with the appropriate word(s).
Compare the rate of condensate flow from the pipe in Problem 8.28 (air pressure = 200 kPa) with that for a 3.89-cm-OD pipe and 200 kPa air pressure. What is the rate of condensate flow if the 2 cm pipe is submerged in a 20°C constant-temperature water bath?
GIVEN
• A long horizontal copper pipe carrying saturated steam within an environmental testing chamber or a water bath
• Steam pressure = 120 kPa
• Ambient pressure (P) = 2 atm
• Ambient air or water temperature (T?) = 20°C
FIND
Rate of condensate flow for
(a) Diameter (D) = 3.89 cm = 0.0389 m Fluid is air at 2.0 atm
(b) Diameter (D) = 2 cm = 0.02 m Fluid is water at T? = 20°C
ASSUMPTIONS
• Pressure change has no effect on absolute viscosity, thermal conductivity, or specific heat of the air
• Air is still
• Convective thermal resistance on the inside of the pipe is negligible
• Thermal resistance of the copper pipe is negligible
• The air behaves as an ideal gas
SKETCH
PROPERTIES AND CONSTANTS
For saturated steam at 0.12 MPa, the heat of vaporization (hfg) = 2238 kJ/kg, and the temperature (Ts) = 105°C.
for dry air at the mean temperature of 62.5°C and one atmosphere
Thermal expansion coefficient (?) = 0.00298 1/K
Thermal conductivity (k) = 0.0281 W/(m K)
Prandtl number (Pr) = 0.71 at P = 2.0 Atm,
Kinematic viscosity (?) = 9.83 × 10–6 Ns/m2
Kinetic Energy: A space barge pushes on a spaceship with a mass of 15,000 kg and accelerates it from a speed of 0.600c to a speed of 0.700c. How much work does the barge have to do to accomplish this? (c = 3.00 × 108 m/s)
A. 1.35 × 1020 J B. 2.03 × 1020 J C. 2.70 × 1020 J D. 5.42 × 1020 J E. 8.78 × 1019 J
If a hydrogen atom in the ground state absorbs a photon of energy 12.09 eV, to which energy state will it make a transition?
A) n = 2 B) n = 3 C) n = 4 D) n = 5