Convert the following to scientific notation Distance from Sun 92960000 miles Estimated Age of universe 14000000000 Convert the following to standard form Speed of light 90 10 ID: 783144
Download The PPT/PDF document "Gravity 10/5 What comes to mind when you..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Gravity
Slide210/5
What comes to mind when you hear the word gravity?
Convert the following to scientific notation
Distance from Sun
: 92,960,000
miles ____
Estimated Age of universe – 14,000,000,000
Convert the following to standard form
Speed of light = 9.0 * 10
8
m/s
Gravitational constant
= 6.66*10
-11
Slide3Multiplying in Scientific Notation
Slide4Multiplying…
The general format for multiplying is as follows…
(N x 10
x
)(M x 10
y
) = (N)(M) x 10
x+y
First multiply the N and M numbers together and express an answer.
Secondly multiply the exponential parts together by adding the exponents together.
Slide5Multiplying…
Finally multiply the two results for the final answer.
(2.41 x 10
4
)(3.09 x 10
2
)
2.41 x 3.09 = 7.45
4 + 2 = 6
7.45 x 10
6
Slide6Dividing in Scientific Notation
Slide7Dividing…
The general format for dividing is as follows…
(N x 10
x
)/(M x 10
y
) = (N/M) x 10
x-y
First divide the N number by the M number and express as an answer.
Secondly divide the exponential parts by subtracting the exponent from the exponent in the upper number.
Slide8Dividing…
Finally multiply the two results together to get the final answer.
(4.89 x 10
7
)/(2.74 x 10
4
)
4.89 / 2.74 = 1.78
7 – 4 = 3
1.78 x 10
3
Slide911/22
1. How do you weigh an elephant using only a board, yourself and a fulcrum?
2. Why do you weigh less on a mountain? (universal gravitation)
Slide1010/7
1. What factors does the force of gravity depend on?
2. How did newton change the way we see gravity?
3. What is the difference between weight and mass?
Slide11Newton reasoned that the moon is falling toward Earth for the same reason an apple falls from a tree—they are both pulled by Earth
’
s gravity.
13.1
The Falling Apple
Slide123/7
What comes to mind when you think of
newtons
laws?
1. inertia
2. F=M*A
3. Action reaction
Slide13Newton understood the concept of inertia developed earlier by Galileo.
He knew that without an outside force, moving objects continue to move at constant speed in a straight line.
He knew that if an object undergoes a change in speed or direction, then a force is responsible.
13.1
The Falling Apple
Slide14If the moon did not fall, it would follow a straight-line path.
13.2
The Falling Moon
Slide15This original drawing by Isaac Newton shows how a projectile fired fast enough would fall around Earth and become an Earth satellite.
13.2
The Falling Moon
Slide16Tangential velocity is the
“
sideways
”
velocity—the component of velocity perpendicular to the pull of gravity.
13.2
The Falling Moon
Slide17If the force that pulls apples off trees also pulls the moon into orbit, the circle of the moon
’
s orbit should fall 1.4 mm below a point along the straight line where the moon would otherwise be one second later.
13.2
The Falling Moon
Slide18Newton
’
s theory of gravity confirmed the Copernican theory of the solar system
.
Earth orbits the sun like the moon orbits the earth, constantly being pulled in, while tangential velocity is keeping the object in orbit.
13.3
The Falling Earth
Slide19Universal Gravitation
Gravity acts everywhere in the universe
. The force that causes an apple to fall is the same force that acts on the moon.
What factors does gravity depend on
Slide201. What
are the two things that cause the moon to orbit the earth?
2. What would happen to your weight, if your radius from the center of the Earth doubled?
Slide21Newton
’
s
law of universal gravitation
states that every object attracts every other object with a force that for any two objects is directly proportional to the mass of each object.
Newton deduced that the force decreases as the square of the distance between the centers of mass of the objects increases.
13.4
Newton
’
s Law of Universal Gravitation
Slide22The force of gravity between objects depends on the distance between their centers of mass.
13.4
Newton
’
s Law of Universal Gravitation
Slide23Your weight is less at the top of a mountain because you are farther from the center of Earth.
13.4
Newton
’
s Law of Universal Gravitation
Slide24The Universal Gravitational Constant,
G
The law of universal gravitation can be expressed as an exact equation when a proportionality constant is introduced.
The
universal gravitational constant,
G,
in the equation for universal gravitation describes the strength of gravity.
13.4
Newton
’
s Law of Universal Gravitation
Slide25Philipp von Jolly developed a method of measuring the attraction between two masses.
13.4
Newton
’
s Law of Universal Gravitation
Slide26A simpler method was developed by Philipp von Jolly.
He attached a spherical flask of mercury to one arm of a sensitive balance.
A 6-ton lead sphere was rolled beneath the mercury flask.
The flask was pulled slightly downward.
The gravitational force
F,
between the lead mass and the mercury, was equal to the weight that had to be placed on the opposite end of the balance to restore equilibrium.
F, m
1
,
m
2
, and
d
were all known, so the ratio
G
was calculated:
13.4
Newton
’
s Law of Universal Gravitation
Slide27Butter spray travels outward from the nozzle in straight lines. Like gravity, the
“
strength
”
of the spray obeys an inverse-square law.
13.5
Gravity and Distance: The Inverse-Square Law
Slide28This law applies to the weakening of gravity with distance.
It also applies to all cases where the effect from a localized source spreads evenly throughout the surrounding space.
Examples are light, radiation, and sound.
13.5
Gravity and Distance: The Inverse-Square Law
Slide29Gravitational force is plotted versus distance from Earth
’
s center.
13.5
Gravity and Distance: The Inverse-Square Law
Slide30Field lines represent the gravitational field about Earth.
13.6
Gravitational Field
Slide31As you fall into a hole bored through Earth, your acceleration diminishes. The pull of the mass above you partly cancels the pull below.
13.7
Gravitational Field Inside a Planet
Slide32Newton showed that the ocean tides are caused by
differences
in the gravitational pull of the moon on opposite sides of Earth.
13.9
Ocean Tides
Slide33This difference in pulls across Earth slightly elongates it.
The oceans bulge out about 1 meter on average, on opposite sides of Earth.
Because Earth spins once per day, a fixed point on Earth passes beneath both of these bulges each day, producing two sets of ocean tides per day—two high tides and two low tides.
13.9
Ocean Tides
Slide34The two tidal bulges remain relatively fixed with respect to the moon while Earth spins daily beneath them.
13.9
Ocean Tides
Slide35When the attractions of the sun and the moon are at right angles to each other (at the time of a half moon), neap tides occur.
13.9
Ocean Tides
Slide36The Universal Gravitational Constant,
G
What happens to F if
One mass is half as much
Both masses are twice as much.
The distance is tripled
Hint, substitute a one for every thing then do what the question is asking you to do.
13.4
Newton
’
s Law of Universal Gravitation
Slide37The size of the sun is the result of a
“
tug of war
”
between two opposing processes: nuclear fusion and gravitational contraction.
13.10
Black Holes
Slide38When a massive star collapses into a black hole, there is no change in the gravitational field at any point beyond the original radius of the star
.
You will learn later that our some never becomes a
blackhole
…sorry
13.10
Black Holes
Slide39What would happen to the earth if the sun collapsed into a black hole?
Use the gravity equation to explain why a black hole is so powerful.
A black hole is a place in space where gravity pulls so much that even
light
can not get out.
The
gravity is so strong because matter has been squeezed into a tiny space
.
This can happen when a star is dying.
Slide4010 / 8
- Today
we will be collecting data for the next
CER
If you were plotting mass and force, which would be the dependent variable and which would be the independent variable?
Which axis would you place them on?
http://phet.colorado.edu/en/simulation/gravity-force-lab
Slide41Gravitational force dependent variable
Mass independent variable
Slide42Mass 1
Mass 2 (kg)
Force (10
-11
N)
0
30
30
30
30
30
30
30
30
30
30
distance
force
Copy the following tables in your science notebook.
After completing the first table,
Slide43How to create a graph on
microsoft
excell
http
://www.youtube.com/watch?v=Xn7Sd5Uu42A
mass 1
force
0
0
10
3.00E-10
20
1.05E-09
30
1.57E-09
40
2.09E-09
50
2.62E-09
60
3.14E-09
70
3.66E-09
80
4.19E-09
90
4.71E-09
100
5.23E-09
Slide44How to make a line graph on Microsoft excel
Type the horizontal independent variable values in the left hand column,
Type the dependent y-values in the right column
Highlight numbers
Go to insert – scatter – smooth column
Enter in Labels and titles
- left click on line – click add
trendline
Click on display equation on chart, and
add r-square
value
Slide45Which direction does a
s
un pull on a planet?
Slide46Slide47The gravitational field strength near a giant star that collapses to become a black hole is the same before collapse (left) and after collapse (right).
13.10
Black Holes
Slide48Force and distance will be two of the variables we will be looking at today. Which one would be considered the independent variable and which would be the dependent variable?
Slide49Recent evidence suggests the universe is not only expanding, but
accelerating
outward.
It is pushed by an anti-gravity
dark energy
that makes up an estimated 73 percent of the universe.
Twenty-three percent of the universe is composed of the yet-to-be discovered particles of exotic
dark matter
.
The concepts of dark matter and dark energy will continue to inspire exciting research throughout this century.
13.11
Universal Gravitation
Slide503/13
What is the relationship between gravitational force and distance? (is it reduced by, directly proportional to, independent of)
What would happen to your weight if the volume of the earth was smaller but the mass was the same?
Tomorrow
Gravity quiz
Notebook check
Slide51The Universal Gravitational Constant,
G
What happens to F if
One mass is half as much
Both masses are twice as much.
The distance is tripled
Hint, substitute a one for every thing then do what the question is asking you to do.
13.4
Newton
’
s Law of Universal Gravitation
Slide52Until the middle of the last century astronomers were puzzled by unexplained
perturbations (path changes)
of the planet Uranus.
The source of Uranus
’
s perturbation was uncovered in 1845 and 1846 by two astronomers, John Adams in England and
Urbain
Leverrier
in France.
Applying Newton
’
s law of gravitation, both astronomers concluded that there was a body beyond the orbit of Uranus
.
The planet Neptune was discovered.
13.11
What is up with Uranus?
Slide53Are you ready for the quiz?
Notebook check, dates from
Slide54The size of the sun is the result of a
“
tug of war
”
between two opposing processes: nuclear fusion and gravitational contraction.
13.10
Black Holes
Slide55Blackholes
Gravity always wins!
Future questions
Do black holes have mass?
Slide56Finish gravity post test. Use evidence from your computer simulation to support your reasoning in the last question. What comes to mind when you think of universal gravitation?
Keep variable a one and everything a
Slide57Could you survive a plane crash? Why or why not? How could you test this?
If you dropped a penny from a tall building could it kill a person?
Slide58What did you think of the final?
How do you think you did on the forbidden kingdom final?
Discuss number five
Introduce astronomy presentations part two: gravity
Slide59What are some characteristics of a strong presentation?
Which topic did you decide?
Today
Study your topic and generate two questions
Slide60What comes to mind when you think of gravity?
Slide61This original drawing by Isaac Newton shows how a projectile fired fast enough would fall around Earth and become an Earth satellite.
13.2
The Falling Moon
Slide62What is the main idea behind your presentation?
What is a future question you can ask based on your presentation?
If you weight 160 pounds on the Earth’s surface what would be your weight if you climbed a ladder that was as long as the earths radius?
Slide63The moon was already known to be 60 times farther from the center of Earth than an apple at Earth’s surface.
The apple will fall 5 m in its first second of fall.
Newton reasoned that gravitational attraction to Earth must be “diluted” by distance.
The influence of gravity should be diluted to 1/60 of 1/60.
In one second the moon should fall 1/(60)
2
of 5 m, which is 1.4 millimeters.
13.2
The Falling Moon
Slide64Newton’s
law of universal gravitation
states that every object attracts every other object with a force that for any two objects is directly proportional to the mass of each object.
Newton deduced that the force decreases as the square of the distance between the centers of mass of the objects increases.
13.4
Newton’s Law of Universal Gravitation
The magnitude of
G
is given by the magnitude of the force between two masses of 1 kilogram each, 1 meter apart: 0.0000000000667 newton. (In scientific notation:
G
= 6.67 × 10
−11
N·m
2
/kg
2
)
Slide65Slide66Planet
Semimajor
axis (10
10
m)
PeriodT
(
y
) T
2
/a
3
(10
-34
y
2
/m
3
)
Mercury 5.79 0.241 2.99 Venus 10.8 0.615 3.00 Earth 15.0 1 2.96 Mars 22.8 1.88 2.98 Jupiter 77.8 11.9 3.01 Saturn 143 29.5 2.98 Uranus 287 84 2.98 Neptune 450 165 2.99 Pluto 590 248 2.99
Kepler’s
third law
T
2
/ a
3
period squared = axis cubed
Slide673/14
Are you ready for the quiz?
What are two ways of reducing your weight without exercise or dieting?
Notebook check # of days since 3/3
Hints
Weight is the same thing as force
Slide68What topic did you choose?
What are some strong communication skills?
What are some strong listening skills
Slide69The force of gravity between objects depends on the distance between their centers of mass.
13.4
Newton’s Law of Universal Gravitation
Slide7012/1/10
Think of two questions that your presentation will answer.
Slide7112/2 warm up
Is
your presentation ready?
What is one part that could use work?
Take about 10 minutes to practice your explanations with your group members