What kind of object do we think lies in the center of the Milky Way Galaxy?
A) a black hole of about 4 million solar masses
B) a gigantic x-ray binary system
C) a dense cluster of young, hot stars
D) an enormous collection of dark matter, explaining why we detect no light at all from the galactic center
A) a black hole of about 4 million solar masses
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Coronal holes are holes in the chromosphere to allow the solar wind to stream away from the Sun
a. True b. False Indicate whether the statement is true or false
A 0.600-kg piece of metal X is heated to 100°C and placed in an aluminum can of mass 0.200-kg which contains 0.500 kg of water initially at 17.3°C
The final equilibrium temperature of the mixture is 20.2°C, what is the specific heat of metal X? The specific heats of water and aluminum are 4186 J/kg ? K (water) and 910 J/kg ? K (aluminum). A) 140 J/kg ? K B) 270 J/kg ? K C) 450 J/kg ? K D) 900 J/kg ? K
A thin lens has a focal length of 10.00 cm for blue light. If the index of refraction for the lens material tends to decrease with increasing wavelength, what is the focal length of the lens for red light?
a. more than 10.00 cm b. It depends on whether the lens is converging or diverging. c. also 10.00 cm d. less that 10.00 cm
Two resistors of 5.0 and 9.0 ? are connected in parallel. A 4.0-? resistor is then connected in series with the parallel combination. A 6.0-V battery is then connected to the series-parallel combination
(a) What is the current through the 4.0-? resistor? (b) What is the current through the 5.0-? resistor? (c) What is the current through the 9.0-? resistor?