Although most astronomers assume dark matter really exists, there is at least one other possible explanation for the phenomena attributed to dark matter. What is it?
A) There could be something wrong or incomplete with our understanding of how gravity operates on galaxy-size scales.
B) The so-called dark matter is really just ordinary stars that are enshrouded in clouds of dust.
C) We could just be having a hard time understanding the observations, because they involve very distant galaxies.
D) There could be something wrong with our understanding of how atoms produce light.
A) There could be something wrong or incomplete with our understanding of how gravity operates on galaxy-size scales.
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Why was the Davis experiment only able to detect one-third of the neutrinos originally predicted? a. The number of neutrinos was too great to be held in the tank that Davis designed
b. The neutrinos combined with other particles as they entered Earth's atmosphere. c. The neutrinos distributed evenly among three different flavors while traveling to Earth. d. Most of the neutrinos were absorbed by Earth's atmosphere. e. The other two-thirds of neutrinos dissipated while traveling to Earth.
Inelastic Collisions: A 1000-kg whale swims horizontally to the right at a speed of 6.0 m/s. It suddenly collides directly with a stationary seal of mass 200 kg. The seal grabs onto the whale and holds fast. What is the momentum of these two sea creatures just after their collision? You can neglect any drag effects of the water during the collision.
A. 0.00 kg ? m/s B. 1200 kg ? m/s C. 2000 kg ? m/s D. 7200 kg ? m/s E. 6000 kg ? m/s
A plane flying horizontally at a speed of 50.0 m/s and at an elevation of 160. m drops a package of supplies. Two seconds later it drops a second package. How far apart will the two packages land on the ground?
A) 100. m B) 67.7 m C) 283. m D) 162. m E) 177. m
The theory of seafloor spreading was proposed in 1960 by
a. Alfred Wegener. b. Harry Hess. c. Albert Einstein. d. Andrija Mohorovicic.