Kalfree 2

Homework 2 for Kalfree

Question 1

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  If a tenth planet (tentatively predicted to exist on the basis of perturbations in the orbits of Uranus and Neptune) were to be discovered with a sidereal period of 200 years, what would be the radius of its orbit (assumed to be circular)? 

Answer

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· 1.

· 34.2 AU

· 2.

· 342 AU

· 3.

· 200 AU

· 4.

· 2828 AU

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1 points  

Question 2

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  The one significant observation Galileo made through his home-built telescope that convinced him that the planets revolved around the Sun was the 

Answer

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· discovery of rings around the planet Saturn.

· appearance of mountains and craters on the Moon.

· appearance of the Milky Way as a mass of individual stars.

· appearance of Venus following a cycle of phases, from crescent through · quarter and gibbous phases to full.

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1 points  

Question 3

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  For the angular momentum of an object to be conserved (i.e., to not change), the 

Answer

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· object must not be acted on by an internal torque (caused, for example, · by the muscles in a skater’s arms). ·

· speed of the object must not change.

· size of the object must not change.

· object must not be acted on by an outside torque.

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1 points  

Question 4

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  Who predicted the existence of the planet Neptune before it was discovered observationally? 

Answer

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· Newton and Halley

· Kepler and Brahe

· Kepler and Galileo

· Adams and Leverrier

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1 points  

Question 5

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  The old story about the person who sneezed so hard that he fell off his barstool is an exaggerated illustration of which physical law? 

Answer

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· Newton’s law of universal gravitation

· law forbidding the partaking of alcohol during physical experiments

· Newton’s third law of equal and opposite forces of action and reaction

· law of inertia, Newton’s first law

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1 points  

Question 6

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  If two massive bodies, initially held at rest in space, are released, then they will begin to 

Answer

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· move in elliptical orbits around one another.

· move toward one another.

· orbit one another in circles.

· move away from each other with constant acceleration.

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1 points  

Question 7

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  In the geocentric model for the solar system developed by Ptolemy, to what does the word epicycle refer?


Answer

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· complete cycle of planetary motions after which the motions repeat · themselves (almost) exactly ·

· length of time from when the planet is farthest from the Earth to the · next time it is farthest from the Earth ·

· large circle (orbit) that carries the planet around the Earth while the · planet itself is moving in a smaller circle ·

· small circle about which a planet moves while the center of this circle · moves around the Earth

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1 points  

Question 8

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  In which part of the sky does Venus appear at sunset when it is at greatest elongation? 

Answer

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· eastern

· It is not be visible because it is on the other side of the Sun.

· due south

· western

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1 points  

Question 9

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  An asteroid-like object (or a cometary nucleus) is seen to be orbiting the Sun in a circular path with a period of 120 years. What is its distance of closest approach to Earth (the separation distance when the object is at opposition)? (Be careful with your answer; a diagram might be helpful.) 

Answer

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· 1314.5 AU

· 25.33 AU

· 24.33 AU.

· 23.33 AU

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1 points  

Question 10

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  Which of the following objects could transit (pass in front of) the Sun as seen from Saturn? 

Answer

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· Uranus

· Jupiter

· Neptune

· Pluto