3: Orbits and Gravity

Question 1

the measure of the motion of a rotating object in terms of its speed and how widely the object’s mass is distributed around its axis

Answer 1

angular momentum

Question 2

the point in its orbit where a planet (or other orbiting object) is farthest from the Sun

Answer 2

aphelion

Question 3

the point in its orbit where an Earth satellite is farthest from Earth

Answer 3

apogee

Question 4

the region of the solar system between the orbits of Mars and Jupiter in which most asteroids are located; the main one extends from 2.2 to 3.3 AU from the Sun

Answer 4

asteroid belt

Question 5

the ratio of the mass of an object to its volume

Answer 5

density

Question 6

in an ellipse, the ratio of the distance between the foci to the major axis

Answer 6

eccentricity

Question 7

a closed curve for which the sum of the distances from any point to two points inside (foci) is always the same

Answer 7

ellipse

Question 8

the speed a body must achieve to break away from the gravity of another body

Answer 8

escape speed

Question 9

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

Answer 9

focus (foci)

Question 10

the mutual attraction of material bodies or particles

Answer 10

gravity

Question 11

Kepler: each planet moves around the Sun in an orbit that is an ellipse, with the Sun at one focus of the ellipse

Answer 11

Kepler’s first law

Question 12

Kepler: the straight line joining a planet and the Sun sweeps out equal areas in space in equal intervals of time

Answer 12

Kepler’s second law

Question 13

Kepler: the square of a planet’s orbital period is directly proportional to the cube of the semimajor axis of its orbit

Answer 13

Kepler’s third law

Question 14

the maximum diameter of an ellipse

Answer 14

major axis

Question 15

a measure of the amount of material within an object

Answer 15

mass

Question 16

the measure of the amount of motion of a body - the product of its mass and velocity

Answer 16

momentum

Question 17

Newton: 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

Answer 17

Newton’s first law

Question 18

Newton: the change of motion of a body is proportional to and in the direction of the force acting on it

Answer 18

Newton’s second law

Question 19

Newton: for every action there is an equal and opposite reaction (the mutual actions of two bodies upon each other are always equal and act in opposite directions)

Answer 19

Newton’s third law

Question 20

the path of an object that is in revolution about another object or point

Answer 20

orbit

Question 21

the time it takes an object to travel once around the Sun

Answer 21

orbital period (P)

Question 22

the speed at which an object (usually a planet) moves around the mass of another object; in the case of a planet, the speed at which it moves along its ellipse

Answer 22

orbital speed

Question 23

the point in its orbit where an Earth satellite is closest to Earth

Answer 23

perigee

Question 24

the point in its orbit where a planet (or other orbiting object) is nearest to the Sun

Answer 24

perihelion

Question 25

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

Answer 25

perturbation

Question 26

an object that revolves around a planet

Answer 26

satellite

Question 27

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

Answer 27

semimajor axis

Question 28

the speed and direction a body is moving (ex. 44 kilometers per second toward the north galactic pole)

Answer 28

velocity