Explain differential rotation and Keplerian motion
What will be an ideal response?
The measured motion of stars shows that the disk does not rotate as a solid body. Each star follows its own orbit, and stars in some regions have shorter or longer orbital periods than the Sun. This is called differential rotation.If all of the mass in the galaxy were concentrated at its center, then orbital velocity would be high near the center and would decline away from the center. This kind of motion has been called Keplerian motion because it follows Kepler's third law, as in the case of our Solar System, where nearly all of the mass is in the Sun.
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How is the existence of Earth's unique atmosphere explained?
A) The oxygen in Earth's atmosphere is a result of early life on Earth. B) Volcanic gases containing nitrogen were outgassed from Earth's interior. C) As Earth cooled, water vapor fell out of the atmosphere to form the oceans. D) Ultraviolet radiation from the Sun freed the hydrogen, allowing it to escape. E) When Earth formed, its atmosphere formed from the gases most common in the early solar system.
What is the binding energy of 12C? The mass of an atom of 12C is 12 u (exactly), of an atom of 1H is 1.007825 u, and of a neutron is 1.0086649 u.
A. 137 MeV B. 104 MeV C. 92.2 MeV D. 46.1 MeV E. 7.68 MeV
Boat 1 goes directly across a stream a distance L and back taking a time t1 . Boat 2 goes down stream a distance L and back taking a time t2 . If both boats had the same speed relative to the water, which of the following statements is true?
a. t2 > t1 b. t2 < t1 c. t2 = t1 d. t2 = 2t1 e. t2 = 0.5t1
A force acting on an object moving along the x axis is given by Fx = (14x - 3.0x2) N where x is in m. How much work is done by this force as the object moves from x = -1 m to x = +2 m?
a. +12 J b. +28 J c. +40 J d. +42 J e. -28 J