The location of the Galactic Center was first found by Harlow Shapley with:
A) radio emissions from Sagittarius A.
B) Cepheids of Population I in the spiral arms.
C) RR Lyrae variables in the globular clusters.
D) planetary nebulae in the open clusters.
E) infrared observations of the heat from its accretion disk around the black hole.
C
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Once a protoplanet reached a large mass, what is the next step for it to formally grow into a planet?
a. gravitational collapse b. expanding c. accretion d. condensation e. slowing momentum
A 75 kg road bicycle racer rides down the highway from Pike’s peak. During one stretch of the ride, he descends 150 m while accelerating from 35 km/hr to some 45 km/hr. What work was done by friction and air resistance during this descent?
A. 27.5 kJ B. 70.0 kJ C. 50.2 kJ D. 23.9 kJ E. 36.7 kJ F. 40.3 kJ
A(n) ______ website search provider is a third-party company that uses spiders or other tools to build a searchable index of your website's pages.
A. virtual B. hosted C. cloud D. anchor
A concave mirror has
A) no focal length. B) a positive or negative focal length depending on the object position. C) a positive focal length. D) a negative focal length. E) a positive or negative focal length depending on the object size.