Ch 3 Key Terms

Question 1

Angular momentum

Answer 1

Measure of the motion of a rotating object in terms of its speed and how widely the objects mass is distributed around its axis

Question 2

Aphelion

Answer 2

Point where a planet is farthest from sun in orbit

Question 3

Apogee

Answer 3

Point in its orbit where an earth satellite is farthest from earth

Question 4

Asteroid belt

Answer 4

Region b/w orbits of mars and Jupiter where most asteroids are

Question 5

Astronomical unit

Answer 5

(AU) unit of length defined as avg dist b/w earth and sun

1.5 x 10^8 km

Question 6

Density

Answer 6

Mass divided by vol

Question 7

Eccentricity

Answer 7

In an ellipse, ratio of distance b/w foci to major axis

Question 8

Ellipse

Answer 8

Closed curve for which the sum of the distances from any point on the ellipse to 2 points inside is always the same

Question 9

Escape speed

Answer 9

Speed a body must have in order to break away from gravity of another body

Question 10

Foci

Answer 10

Two fixed points inside an ellipse from which sum of distances to any point on the ellipse is constant

Question 11

Gravity

Answer 11

Mutual attraction of material bodies or particles

Question 12

Keplers first law

Answer 12

Each planet moves around the sun in an orbit that is an ellipse, w the sun at one focus of the ellipse

Question 13

Keplers second law

Answer 13

Straight line joining a planet and the sun sweeps out equal areas in space in equal intervals of time

Question 14

Keplers third law

Answer 14

The square of a planets orbital period is directly proportional to cube of semi major axis of orbit

Question 15

Major axis

Answer 15

Max diameter of an ellipse

Question 16

Momentum

Answer 16

Measure of amount of motion a body has…product of mass/velocity

Question 17

Newton’s first law

Answer 17

Every object will continue to be in a state of rest or move at a constant speed in a straight line unless it is compelled to change by an outside force

Question 18

Newton’s second law

Answer 18

Change of motion of a body is proportional to and in the direction of the force acting on it

Question 19

Newton’s third law

Answer 19

For every action there is an equal and opposite reaction

Question 20

Orbit

Answer 20

Path of an object that is in revolution about another object or point

Question 21

Orbital period (p)

Answer 21

Time it takes an object to travel once around the sun

Question 22

Orbital speed

Answer 22

Speed at which an object orbits around the mass of another object

Question 23

Perigee

Answer 23

Point in its orbit where an earth satellite is closest to earth

Question 24

Perihelion

Answer 24

Point where planet is nearest sun

Question 25

Perturbation

Answer 25

Small disturbing effect on the motion or orbit or a body produced by a third body

Question 26

Satellite

Answer 26

An object that revolves around a planet

Question 27

Semi major axis

Answer 27

Half of the major axis of a conic section, such as an ellipse

Question 28

Velocity

Answer 28

Speed and direction that a body is moving