How do we know that there is much more mass in the halo of our galaxy than in the disk?
A) There are so many globular clusters in the halo that their total mass is greater than the mass of stars in the disk.
B) Stars and gas clouds in the outskirts of the Milky Way orbit the galaxy at much higher speeds than we would expect if all the mass were concentrated in the disk.
C) We have discovered that the halo is filled with an enormous number of brown dwarfs that have a combined mass much greater than the disk.
D) Laboratory experiments have proven that the halo must be full of subatomic dark matter particles.
B) Stars and gas clouds in the outskirts of the Milky Way orbit the galaxy at much higher speeds than we would expect if all the mass were concentrated in the disk.
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When two or more capacitors are connected in parallel across a potential difference,
A) the potential difference across each capacitor is the same. B) each capacitor carries the same amount of charge. C) the equivalent capacitance of the combination is less than the capacitance of any of the capacitors. D) All of the above choices are correct. E) None of the above choices are correct.
Why are elements with even numbers of protons more abundant, on average, than elements with odd numbers of protons?
A) because when elements split in a fission reaction, they prefer to split with all the protons paired B) because elements are mainly made in fusion reactions with hydrogen nuclei C) because elements are mainly made in fusion reactions with helium nuclei D) There's no explanation; it's something of a mystery to be explained or it may be a coincidence.
A proton is accelerated from rest through a potential difference of 150 V. It then enters a region of uniform magnetic field and moves in a circular path (radius = 12 cm). What is the magnitude of the magnetic field in this region?
a. 18 mT b. 12 mT c. 15 mT d. 22 mT e. 10 mT
Io's internal heat is due to tidal interactions with Jupiter and Europa
Indicate whether the statement is true or false