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129 Cards in this Set

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List the 3 terms used to describe motion in science:
1. speed
2. velocity
3. acceleration
What is the term used tell us how far an object will travel in a certain amount of time?
Speed
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?
Velocity
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?
Acceleration
What is the term used that tells a moving object's speed and direction?
Velocity
What is the term used that tells a moving object's changing velocity?
Acceleration
T or F
In science, an object is accelerating when it slows down or it turns>
True
What is happening to an object when its acceleration is in a direction opposite to its motion?
The object is SLOWING
How do we describe the acceleration of a slowing object?
The acceleration is negative
When an object's acceleration is negative, what is happening to its velocity?
The velocity decreases
T or F
Turning is a form of acceleration even if an object's speed remains constant.
True
How does gravity act on a falling object?
It makes the object accelerate as it falls
T or F
Galileo demonstrated that gravity does not accelerate all object by the same amount, regardless of their mass.
False,
Galileo demonstrated that gravity does accelerate all objects by the same amount, regardless of their mass.
T or F
Air resistance does not cause a difference in acceleration of moving objects.
False
Air resistance does cause a difference in acceleration of moving objects.
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.
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.
What is the term for the acceleration of a falling object?
Acceleration of gravity
What is the abbreviation for the acceleration of gravity?
g.
On Earth, the acceleration of gravity (g) causes falling objects to fall faster by how much?
9.8 meters per second (m/s) with each passing second
After 1 second after dropping a rock from a tall building 10 m/s. After 2 seconds, how fast is this rock traveling?
20 m/s.
What is the numeric representation for the acceleration of gravity?
@ 10 meters per second per second OR
2
10 m/s
OR 10 meters per second squared
in scientific motion formulas, what is usually the abbrev. for time?
t
In scientific motion formulas, what is usually the abbrev. for velocity?
v
What is the term for an object's combination of mass and velocity?
Momentum
What is the term for
mass X velocity?
Momentum
What is the only way to change an objects momentum?
Apply a force to it.
T or F
The mere presence of a force always causes a change in momentum.
False.
The mere presence of a force DOES NOT always cause a change in momentum
What is the term used to describe the overall force?
Net force
What is the term used that represents the combined effect of all the individual forces put together?
Net force
T or F
An object must accelerate whenever a net force acts on it.
True
T or F
Changing an object's momentum means changing tis velocity, as long as its mass remains constant.
True
T or F
The presence of a net force causes an object to accelerate.
True
T or F
Whenever an object accelerates a net force must be causing the acceleration.
True
T or F
Planets are always accelerating as they orbit the Sun?
True
Why are planets always accelerating as they orbit the Sun?
Because their direction of travel constantly changes as they go around their orbits?
What is the force that causes the planets' acceleration as they orbit the Sun?
Gravity
Who discovered that the force that causes planets to always accelerate as they orbit the Sun?
Isaac Newton
What is the term for the amount of matter in an object?
Mass
What is the term used to describe a force that is acting on an object's mass?
Weight
What happens to the measured weight of an object sitting on a scale in an elevator as it accelerates?
It varies.
What happens to the measured weight of an object sitting on a scale in an elevator as travels at a constant speed?
It remains "normal"
T or F
Mass does not vary based on location.
True
T or F
Weight of an object does not vary based on the forces acting on it.
False,
Weight of an object varies based on the forces acting on it.
T or F
An object's mass varies based on the forces acting on the object.
False.
An object's mass DOES NOT vary based on the forces acting on the object.
What is the term used for "falling without any resistance to slow down an object."
Free-fall
T or F
People or objects are weightless whenever they are falling freely.
True
T or F
Astronauts in orbit are weightless because they are in a constant state of free-fall.
True
T or F
Astronauts are weightless because there is not gravity in space.
False, it is because they are in a constant state of free-fall.
Who is credited with delivering the final blow to Aristotle's theories of physics?
Newton
Why is Newton credited with heralding the birth of modern astrophysics?
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.
Who wrote the book, Philosphiae Naturalis Prinipia Mathematica or "Mathematical Principles of Natural Philosophy"
Isaac Newton
When did Newton write his book, Mathematical Principles of Natural Philosophy?
1687
How many laws of motion are in Newton's Laws of Motion?
3
Cite Newton's first law of motion:
In the absence of a net force, an object will move with constant velocity.
What is the velocity of an object at rest?
v = 0
What is the second part to Newton's first law of motion?
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.
Why does interplanetary spacecraft need no fuel to keep going after they are launched into space?
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
Why is it that when you are traveling in an airplane on a smooth fight, you don't feel any sensations of motion?
As long as the plane is traveling at constant velocity, NO NET FORCE is acting on the plane or you.
What is Newton's Second Law of Motion?
A newt force will change an object's momentum, accelerating it in the direction of the force.
How is Newton's Second Law of Motion written in the form of an equation?
force = mass X acceleration
What is the abbreviated version of the formula for Newton's Second Law of Motion?
F = ma
Which of Newton's Laws of Motion explain why large planets have a greater effect on asteroids and comets than small planets?
Newton's Second Law of Motion
What happens to the acceleration of two objects with different masses change with equal force is applied to both?
Acceleration will be different for the two objects with different masses
What is Newton's Third Law of Motion?
Any force is always paired with an equal and opposite reaction force.
Which of Newton's Laws of Motion explains that objects always attract each other through gravity.
Newton's Third Law of Motion.
What is the law of conservation of momentum?
The total momentum of all interacting objects always stays the same.
Name the three conservation laws that are important to astronomy:
1. conservation of momentum
2. conservation of angular momentum
3. conservation of energy
Describe the law of conservation of angular momentum:
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.
Which law of conservation describes the special type of momentum that is used to describe objects turning in circles or going around curves?
Law of Conservation of Angular Momentum
What is the formula used to represent angular momentum?
angular momentum = m X v X r

m = mass
v = speed or velocity
r = radius
Why is Earth's orbital angular momentum always stays the same?
There are no objects around to give or take angular momentum from Earth as it orbits the Sun
What law tells us why Kepler's second law of planetary motion is true?
Law of Conservation of Angular Momentum
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).
True
T or F
Energy is always conserved, it can be neither created nor destroyed.
True
Describe the Law of Conservation of Energy:
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.
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.
Law of Conservation of Energy
What makes matter move?
Energy
List the 3 major categories of energy:
1. kinetic energy
2. radiative energy
3. potential energy
What is the term for the energy of motion?
kinetic energy
What Greek word means "motion"?
kinetic
What is the term for energy that is carried by light?
Radiative energy
T or F
All light carries energy.
True
T or F
Light can cause changes in matter.
True
What is the term for energy that is stored?
Potential energy
T or F
A rock perched on a ledge has gravitational potential energy because it will fall if it slips off the edge.
True
Gasoline has what type of potential energy that can be converted into the kinetic energy of the moving car.
Chemical potential energy
In science, what is the standard unit of energy?
Joule
In astronomy, what is the most important subcategory of kinetic energy?
Thermal Energy
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?
Thermal Energy
T or F
Temperature and thermal energy are the same thing.
False.
Temperature and thermal energy are NOT quite the same thing.
What does temperature measure?
the AVERAGE kinetic energy of the particles.
What measures the TOTAL kinetic energy of all randomly moving particles in a substance?
Thermal Energy
T or F
Kelvin temperature scale has negative numbers.
False
Kelvin temperature scale does NOT have negative numbers.
Why doesn't Kelvin temperature scale have negative numbers?
It starts at the coldest possible known.
What is the term for the coldest possible known?
Absolute Zero
What happens to random motions of particles of an object when it reaches absolute zero?
There are no random motions at all.
T or F
Thermal energy depends on temperature.
True
What is the term for the numbers of molecules in a given amount of space in an object or material?
Density
T or F
The air has a greater density than water.
False,
Air has a lower density than water.
T or F
Thermal energy depends on the density of the particles in an object.
True
List the 2 most important types of potential energy there are in astronomy:
1. gravitational potential energy
2. mass-energy
What is the term used for the potential energy of mass?
mass-energy
An object has _______ gravitational potential energy when it is higher, and ______ when it is lower.
An object has MORE gravitational potential energy when it is higher and LESS when it is lower.
When you throw a ball up in the air, at what location does the ball have the most potential energy?
At the balls highest point in the air.
As a ball is thrown into the air, what happens to the ball's kinetic energy?
Kinetic energy increases as it becomes close to the ground.
T or F
When a ball is thrown into the air, kinetic energy increases when the balls gravitational potential energy decreases
True
Who discovered that mass is a form of potential energy?
Einstein
How is the amount of potential energy contained in mass represented in a formula?
2
E = mc

E = potential energy
m = mass of the object
c = speed of light
What equation tells us that a small amount of mass contains a huge amount of energy?
2
E = mc
T or F
Einstein's formula for mass-energy tells us that energy can be transformed into mass
True
What is the name for the large machines that search for undiscovered particles of matter in order to create subatomic particles from energy?
Particle accelerators
What is the name for the beginning of the universe in which all matter and energy is thought to have come into existence?
The "Big Bang"
T or F
According to present understanding, th total energy content of the universe was determined in the Big Bang
True
In astronomy, what is the most important force?
Gravity
What are the 3 statements that summarize Newton's universal law of gravitation?
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
T or F
Gravitational force follows an inverse square law with distance.
True
T or F
Doubling the distance between 2 objects weakens the force of
2
gravity by a factor of 2 , or 4
True
What is the term for the sum of its kinetic and gravitational potential energies?
Orbital Energy
T or F
Orbits cannot change spontaneously.
True
How might 2 objects traveling in space feel the effects of each other's gravity?
via a Gravitational encounter
What is the term for when friction can cause objects to lose orbital energy?
Atmospheric drag
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?
Escape Velocity
What is the escape of velocity from Earth's surface?
@ 40,000km/hr or 11 km/s
T or F
The strength of gravity declines with distance.
True
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?
Tidal force
What causes the entire Earth to stretch along the Earth-Moon line, creating 2 tidal bulges?
Tidal forces
What causes the ocean tides each day?
The tidal forces of the Moon.
Why do we always see the same face of the Moon?
Earth's exertion of tidal forces on the Moon
T or F
The Sun affects the ocean tides, its tidal force on the Earth is 1/3 that of the Moon.
True
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?
Neap tides