The figure shows an image of our galaxy, the Milky Way, at dust-penetrating wavelengths. It can be classified as which one of the following galactic types?
A. spiral
B. irregular
C. elliptical
D. red giant
Answer: A. spiral
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Gravitational Force: ?MassRadiusOrbital radiusOrbital periodMoon A4.0 × 1020 kgunknown2.0 × 108 m4.0 × 106 sMoon B1.5 × 1020 kg2.0 × 105 m3.0 × 108 munknownMithra is an unknown planet that has two moons, A and B, in circular orbits around it. The table summarizes the hypothetical data about these moons. What is the magnitude of the maximum gravitational force that Moon A exerts on Moon B? (G = 6.67 × 10-11 N ? m2/kg2)
A. 1.6 × 1013 N B. 4.4 × 1013 N C. 1.0 × 1014 N D. 2.0 × 1014 N E. 4.0 × 1014 N
A torque of 12 N • m is applied to a solid, uniform disk of radius 0.50 m, causing the disk to accelerate at 5.7 rad/s2. What is the mass of the disk?
A) 17 kg B) 13 kg C) 8.5 kg D) 4.3 kg
In a neutron star, the core is
A) primarily iron and silicon. B) electrons and protons packed so tightly they are in contact. C) made of compressed neutrons in contact with each other. D) no longer rotating. E) constantly expanding and contracting.
An ionized atom having Z protons has had all but one of its electrons removed. If E is the total energy of the ground state electron in atomic hydrogen, then what is the total energy of the remaining electron in the ionized atom?
A) ZE B) E/Z C) E D) Z2E E) E/Z2