Astro 105 Sfa Ch4

Front 1

List the 3 terms used to describe motion in science:

Back 1

1. speed
2. velocity
3. acceleration

Front 2

What is the term used tell us how far an object will travel in a certain amount of time?

Back 2

Speed

Front 3

What is the term used to tell us how far an object will travel in a certain amount of time and in a certain direction?

Back 3

Velocity

Front 4

What is the term used to tell us how far an object will travel in a certain amount of time and in a certain direction and the CHANGE in either speed or direction?

Back 4

Acceleration

Front 5

What is the term used that tells a moving object's speed and direction?

Back 5

Velocity

Front 6

What is the term used that tells a moving object's changing velocity?

Back 6

Acceleration

Front 7

T or F
In science, an object is accelerating when it slows down or it turns>

Back 7

True

Front 8

What is happening to an object when its acceleration is in a direction opposite to its motion?

Back 8

The object is SLOWING

Front 9

How do we describe the acceleration of a slowing object?

Back 9

The acceleration is negative

Front 10

When an object's acceleration is negative, what is happening to its velocity?

Back 10

The velocity decreases

Front 11

T or F
Turning is a form of acceleration even if an object's speed remains constant.

Back 11

True

Front 12

How does gravity act on a falling object?

Back 12

It makes the object accelerate as it falls

Front 13

T or F
Galileo demonstrated that gravity does not accelerate all object by the same amount, regardless of their mass.

Back 13

False,
Galileo demonstrated that gravity does accelerate all objects by the same amount, regardless of their mass.

Front 14

T or F
Air resistance does not cause a difference in acceleration of moving objects.

Back 14

False
Air resistance does cause a difference in acceleration of moving objects.

Front 15

T or F
If you dropped a feather and a rock on the Moon, where there is no air, the rock would fall faster than the feather.

Back 15

False
If you dropped a feather and a rock on the Moon, where there is no air, both would fall at exactly the same rate.

Front 16

What is the term for the acceleration of a falling object?

Back 16

Acceleration of gravity

Front 17

What is the abbreviation for the acceleration of gravity?

Back 17

g.

Front 18

On Earth, the acceleration of gravity (g) causes falling objects to fall faster by how much?

Back 18

9.8 meters per second (m/s) with each passing second

Front 19

After 1 second after dropping a rock from a tall building 10 m/s. After 2 seconds, how fast is this rock traveling?

Back 19

20 m/s.

Front 20

What is the numeric representation for the acceleration of gravity?

Back 20

@ 10 meters per second per second OR
2
10 m/s
OR 10 meters per second squared

Front 21

in scientific motion formulas, what is usually the abbrev. for time?

Back 21

t

Front 22

In scientific motion formulas, what is usually the abbrev. for velocity?

Back 22

v

Front 23

What is the term for an object's combination of mass and velocity?

Back 23

Momentum

Front 24

What is the term for
mass X velocity?

Back 24

Momentum

Front 25

What is the only way to change an objects momentum?

Back 25

Apply a force to it.

Front 26

T or F
The mere presence of a force always causes a change in momentum.

Back 26

False.
The mere presence of a force DOES NOT always cause a change in momentum

Front 27

What is the term used to describe the overall force?

Back 27

Net force

Front 28

What is the term used that represents the combined effect of all the individual forces put together?

Back 28

Net force

Front 29

T or F
An object must accelerate whenever a net force acts on it.

Back 29

True

Front 30

T or F
Changing an object's momentum means changing tis velocity, as long as its mass remains constant.

Back 30

True

Front 31

T or F
The presence of a net force causes an object to accelerate.

Back 31

True

Front 32

T or F
Whenever an object accelerates a net force must be causing the acceleration.

Back 32

True

Front 33

T or F
Planets are always accelerating as they orbit the Sun?

Back 33

True

Front 34

Why are planets always accelerating as they orbit the Sun?

Back 34

Because their direction of travel constantly changes as they go around their orbits?

Front 35

What is the force that causes the planets' acceleration as they orbit the Sun?

Back 35

Gravity

Front 36

Who discovered that the force that causes planets to always accelerate as they orbit the Sun?

Back 36

Isaac Newton

Front 37

What is the term for the amount of matter in an object?

Back 37

Mass

Front 38

What is the term used to describe a force that is acting on an object's mass?

Back 38

Weight

Front 39

What happens to the measured weight of an object sitting on a scale in an elevator as it accelerates?

Back 39

It varies.

Front 40

What happens to the measured weight of an object sitting on a scale in an elevator as travels at a constant speed?

Back 40

It remains "normal"

Front 41

T or F
Mass does not vary based on location.

Back 41

True

Front 42

T or F
Weight of an object does not vary based on the forces acting on it.

Back 42

False,
Weight of an object varies based on the forces acting on it.

Front 43

T or F
An object's mass varies based on the forces acting on the object.

Back 43

False.
An object's mass DOES NOT vary based on the forces acting on the object.

Front 44

What is the term used for "falling without any resistance to slow down an object."

Back 44

Free-fall

Front 45

T or F
People or objects are weightless whenever they are falling freely.

Back 45

True

Front 46

T or F
Astronauts in orbit are weightless because they are in a constant state of free-fall.

Back 46

True

Front 47

T or F
Astronauts are weightless because there is not gravity in space.

Back 47

False, it is because they are in a constant state of free-fall.

Front 48

Who is credited with delivering the final blow to Aristotle's theories of physics?

Back 48

Newton

Front 49

Why is Newton credited with heralding the birth of modern astrophysics?

Back 49

Newton realized that gravity operated in the heavens as well as on Earth, that physical laws discovered on Earth are applicable to phenomena throughout the cosmos.

Front 50

Who wrote the book, Philosphiae Naturalis Prinipia Mathematica or "Mathematical Principles of Natural Philosophy"

Back 50

Isaac Newton

Front 51

When did Newton write his book, Mathematical Principles of Natural Philosophy?

Back 51

1687

Front 52

How many laws of motion are in Newton's Laws of Motion?

Back 52

3

Front 53

Cite Newton's first law of motion:

Back 53

In the absence of a net force, an object will move with constant velocity.

Front 54

What is the velocity of an object at rest?

Back 54

v = 0

Front 55

What is the second part to Newton's first law of motion?

Back 55

Objects at rest tend to remain at rest, and objects in motion tend to remain in motion with no change in either their speed or their direction.

Front 56

Why does interplanetary spacecraft need no fuel to keep going after they are launched into space?

Back 56

Objects in motion tend to remain in motion with no change in either their speed or their direction or
NEWTON'S FIRST LAW OF MOTION

Front 57

Why is it that when you are traveling in an airplane on a smooth fight, you don't feel any sensations of motion?

Back 57

As long as the plane is traveling at constant velocity, NO NET FORCE is acting on the plane or you.

Front 58

What is Newton's Second Law of Motion?

Back 58

A newt force will change an object's momentum, accelerating it in the direction of the force.

Front 59

How is Newton's Second Law of Motion written in the form of an equation?

Back 59

force = mass X acceleration

Front 60

What is the abbreviated version of the formula for Newton's Second Law of Motion?

Back 60

F = ma

Front 61

Which of Newton's Laws of Motion explain why large planets have a greater effect on asteroids and comets than small planets?

Back 61

Newton's Second Law of Motion

Front 62

What happens to the acceleration of two objects with different masses change with equal force is applied to both?

Back 62

Acceleration will be different for the two objects with different masses

Front 63

What is Newton's Third Law of Motion?

Back 63

Any force is always paired with an equal and opposite reaction force.

Front 64

Which of Newton's Laws of Motion explains that objects always attract each other through gravity.

Back 64

Newton's Third Law of Motion.

Front 65

What is the law of conservation of momentum?

Back 65

The total momentum of all interacting objects always stays the same.

Front 66

Name the three conservation laws that are important to astronomy:

Back 66

1. conservation of momentum
2. conservation of angular momentum
3. conservation of energy

Front 67

Describe the law of conservation of angular momentum:

Back 67

1.Total angular momentum can never change. AND
2. an individual object can change its angular momentum only by transferring some angular momentum to or from another object.

Front 68

Which law of conservation describes the special type of momentum that is used to describe objects turning in circles or going around curves?

Back 68

Law of Conservation of Angular Momentum

Front 69

What is the formula used to represent angular momentum?

Back 69

angular momentum = m X v X r

m = mass
v = speed or velocity
r = radius

Front 70

Why is Earth's orbital angular momentum always stays the same?

Back 70

There are no objects around to give or take angular momentum from Earth as it orbits the Sun

Front 71

What law tells us why Kepler's second law of planetary motion is true?

Back 71

Law of Conservation of Angular Momentum

Front 72

T or F
Earth's orbital speed must be faster when it is nearer to the Sun (and the radius is shorter) and slower when it is farther from the Sun (and the radius is longer).

Back 72

True

Front 73

T or F
Energy is always conserved, it can be neither created nor destroyed.

Back 73

True

Front 74

Describe the Law of Conservation of Energy:

Back 74

Energy can be transferred from one object to another or transformed from one type to another, but the total amount of energy is always conserved.

Front 75

What law of Conservation is :
Energy can be transferred from one object to another or transformed from one type to another, but the total amount of energy is always conserved.

Back 75

Law of Conservation of Energy

Front 76

What makes matter move?

Back 76

Energy

Front 77

List the 3 major categories of energy:

Back 77

1. kinetic energy
2. radiative energy
3. potential energy

Front 78

What is the term for the energy of motion?

Back 78

kinetic energy

Front 79

What Greek word means "motion"?

Back 79

kinetic

Front 80

What is the term for energy that is carried by light?

Back 80

Radiative energy

Front 81

T or F
All light carries energy.

Back 81

True

Front 82

T or F
Light can cause changes in matter.

Back 82

True

Front 83

What is the term for energy that is stored?

Back 83

Potential energy

Front 84

T or F
A rock perched on a ledge has gravitational potential energy because it will fall if it slips off the edge.

Back 84

True

Front 85

Gasoline has what type of potential energy that can be converted into the kinetic energy of the moving car.

Back 85

Chemical potential energy

Front 86

In science, what is the standard unit of energy?

Back 86

Joule

Front 87

In astronomy, what is the most important subcategory of kinetic energy?

Back 87

Thermal Energy

Front 88

What type of energy represents the collective kinetic energy of the many individual particles within a substance like a rock or the air or the gas within a distant star?

Back 88

Thermal Energy

Front 89

T or F
Temperature and thermal energy are the same thing.

Back 89

False.
Temperature and thermal energy are NOT quite the same thing.

Front 90

What does temperature measure?

Back 90

the AVERAGE kinetic energy of the particles.

Front 91

What measures the TOTAL kinetic energy of all randomly moving particles in a substance?

Back 91

Thermal Energy

Front 92

T or F
Kelvin temperature scale has negative numbers.

Back 92

False
Kelvin temperature scale does NOT have negative numbers.

Front 93

Why doesn't Kelvin temperature scale have negative numbers?

Back 93

It starts at the coldest possible known.

Front 94

What is the term for the coldest possible known?

Back 94

Absolute Zero

Front 95

What happens to random motions of particles of an object when it reaches absolute zero?

Back 95

There are no random motions at all.

Front 96

T or F
Thermal energy depends on temperature.

Back 96

True

Front 97

What is the term for the numbers of molecules in a given amount of space in an object or material?

Back 97

Density

Front 98

T or F
The air has a greater density than water.

Back 98

False,
Air has a lower density than water.

Front 99

T or F
Thermal energy depends on the density of the particles in an object.

Back 99

True

Front 100

List the 2 most important types of potential energy there are in astronomy:

Back 100

1. gravitational potential energy
2. mass-energy

Front 101

What is the term used for the potential energy of mass?

Back 101

mass-energy

Front 102

An object has _______ gravitational potential energy when it is higher, and ______ when it is lower.

Back 102

An object has MORE gravitational potential energy when it is higher and LESS when it is lower.

Front 103

When you throw a ball up in the air, at what location does the ball have the most potential energy?

Back 103

At the balls highest point in the air.

Front 104

As a ball is thrown into the air, what happens to the ball's kinetic energy?

Back 104

Kinetic energy increases as it becomes close to the ground.

Front 105

T or F
When a ball is thrown into the air, kinetic energy increases when the balls gravitational potential energy decreases

Back 105

True

Front 106

Who discovered that mass is a form of potential energy?

Back 106

Einstein

Front 107

How is the amount of potential energy contained in mass represented in a formula?

Back 107

2
E = mc

E = potential energy
m = mass of the object
c = speed of light

Front 108

What equation tells us that a small amount of mass contains a huge amount of energy?

Back 108

2
E = mc

Front 109

T or F
Einstein's formula for mass-energy tells us that energy can be transformed into mass

Back 109

True

Front 110

What is the name for the large machines that search for undiscovered particles of matter in order to create subatomic particles from energy?

Back 110

Particle accelerators

Front 111

What is the name for the beginning of the universe in which all matter and energy is thought to have come into existence?

Back 111

The "Big Bang"

Front 112

T or F
According to present understanding, th total energy content of the universe was determined in the Big Bang

Back 112

True

Front 113

In astronomy, what is the most important force?

Back 113

Gravity

Front 114

What are the 3 statements that summarize Newton's universal law of gravitation?

Back 114

1. Every mass attracts every other mass through the force called gravity.
2. Strength of the gravitational force attracting any 2 objects is directly proportional to the product of their masses.
3. Strength of gravity between 2 objects decreases with the square of the distance between their centers

Front 115

T or F
Gravitational force follows an inverse square law with distance.

Back 115

True

Front 116

T or F
Doubling the distance between 2 objects weakens the force of
2
gravity by a factor of 2 , or 4

Back 116

True

Front 117

What is the term for the sum of its kinetic and gravitational potential energies?

Back 117

Orbital Energy

Front 118

T or F
Orbits cannot change spontaneously.

Back 118

True

Front 119

How might 2 objects traveling in space feel the effects of each other's gravity?

Back 119

via a Gravitational encounter

Front 120

What is the term for when friction can cause objects to lose orbital energy?

Back 120

Atmospheric drag

Front 121

What is the term for the speed necessary for an object to completely escape the gravity of a large body such as a moon, planet, or star?

Back 121

Escape Velocity

Front 122

What is the escape of velocity from Earth's surface?

Back 122

@ 40,000km/hr or 11 km/s

Front 123

T or F
The strength of gravity declines with distance.

Back 123

True

Front 124

What is the name of the force that is caused when the gravity pulling on one side of an object is larger than that on the other side, causing the object to stretch?

Back 124

Tidal force

Front 125

What causes the entire Earth to stretch along the Earth-Moon line, creating 2 tidal bulges?

Back 125

Tidal forces

Front 126

What causes the ocean tides each day?

Back 126

The tidal forces of the Moon.

Front 127

Why do we always see the same face of the Moon?

Back 127

Earth's exertion of tidal forces on the Moon

Front 128

T or F
The Sun affects the ocean tides, its tidal force on the Earth is 1/3 that of the Moon.

Back 128

True

Front 129

What is the term used for the tides that are created as a result when the tidal forces of the Sun and the Moon counteract each other?

Back 129

Neap tides