The event horizon of a black hole is the point where _____.
a. the mass of the black hole is concentrated in a singularity
b. the accretion disk around the black hole contacts its surface
c. the escape velocity equals the speed of light
d. tidal forces ionize infalling gas
e. an infalling particle reaches equilibrium with radiation pressure
Question 2
What was Eratosthenes's mathematical contribution to the history of astronomy, even though it was incorrect?
a. He calculated the diameter of Earth by what he learned from travelers' itineraries.
b. He estimated Earth's revolution rate by measuring the length of shadows casted on the surface.
c. He determined that all the planets orbited Earth every 24 hrs.
d. He attempted to calculate Earth's radius by utilizing the position of sunlight.
e. He believed all of nature was underlain by musical principles.
The effective temperature, or black body temperature, of the Sun (5777 K) is the temperature a black
Black Raspberry
Label the four mutated DNA segments shown below according to the type of point mutation each ...
Using a black light to spot leaks after adding dye to the oil.
Labeling of black cohosh
A genetic map showing the location of revertible (point) mutants of the rll region