chapter 1 Flashcards

(27 cards)

1
Q

retrograde motion

A

the backward (westward) loops

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2
Q

geocentric

A

the Earth lay at the center of the universe and all other bodies moved.

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3
Q

epicycle

A

first step toward this new model, each planet was taken to move uniformly around a small circle.

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4
Q

deferent

A

center moved uniformly around the earth on a second and larger circle.

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5
Q

ptolemaic model

A

a series of no fewer than 80 circles.

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6
Q

heliocentric

A

sun-centered model

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7
Q

retrograde motion

A

backward, westward loop traced out by a planet with respect to the fixed stars.

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8
Q

copernican revolution

A

the realization, toward the end of the 6th century, the earth is not at the center of the universe.

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9
Q

laws of planetary motion

A

three laws derived by Kepler describing the motion of the planets around the sun.

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10
Q

ellipse

A

geometric figure resembling an elongated circle.

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11
Q

focus

A

one of two special points within an ellipse, whose separation from each other indicates the eccentricity.

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12
Q

semimajor axis

A

one-half of the major axis of an ellipse.

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13
Q

eccentricity

A

a measure of the flatness of an ellipse, equal to the distance between the two foci divided by the length of the major axis.

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14
Q

perihelion

A

the closet approach to the sun of any object in orbit about it.

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15
Q

aphelion

A

the point of the elliptical path of an object in orbit about the sun that is most distant from the sun.

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16
Q

period

A

the time needed for orbiting the body to complete one revolution about another body.

17
Q

astronomical unit

A

the average distance of earth from the sun.

18
Q

radar

A

acronym for radio detection and ranging.

19
Q

newtonian mechanics

A

the basic laws of motion postulated by newton, which are sufficient to explain and quantify virtually all of the complex dynamical behavior found on earth and elsewhere in the universe.

20
Q

force

A

action on an object that causes its momentum to change.

21
Q

inertia

A

the tendency of an object to continue moving at the same speed and in the same direction, unless acted upon by a force.

22
Q

mass

A

a measure of the total amount of matter contained within an object.

23
Q

accerleration

A

the rate of change of velocity of a moving object.

24
Q

gravity

A

the attractive effect that any massive object has on all other massive objects. The greater the mass of the object, the stronger its gravitational pull.

25
gravitational force
force exerted on one body by another due to the effect of gravity.
26
inverse-square law
the law that a field follows if its strength decreases with the square of the distance.
27
center of mass
the "average" position in space of a collection of massive bodies, weighted by their masses.