What range of astronomical distances can we currently measure using both Cepheids and distant standards (white dwarf supernovae)?
What will be an ideal response?
From approximately 10 million to 100 million light-years
You might also like to view...
Which of the following statements best describes what is "relative" in the theory of relativity?
A) The theory says that measurements of motion make sense only when we state what they are measured relative to. B) The theory says that everything is relative. C) The theory says that the speed of light is relative and depends on who is measuring it. D) The theory says that truth can never be established in any absolute sense. Answer: A
Based on inventoried matter in the universe, including dark matter known to exist in galaxies and clusters, the actual density of the universe is what fraction of the critical density?
A) 1 percent B) 10 percent C) 26 percent D) 74 percent E) 100 percent
When humans get cold, they shiver in order to increase their body temperature. Which of the key properties of life is this an example of?
A) growth and development B) reproduction C) order D) response to environment
A plane wall, 7.5 cm thick, generates heat internally at the rate of 105 W/m3 . One side of the wall is insulated, and the other side is exposed to an environment at 90°C. The convection heat transfer coefficient between the wall and the environment is 500 W/(m2 K). If the thermal conductivity of the wall is 12 W/(m K), calculate the maximum temperature in the wall.
GIVEN
FIND
- The maximum temperature in the wall (Tmax)
ASSUMPTIONS
- The heat loss through the insulation is negligible
- The system has reached steady state
- One dimensional conduction through the wall
SKETCH
