Transcript The revolution starts with You!!!

Or…
Don’t let Gravity get you
down
 For the next clip, write down what you think is going through
the person’s mind at the time. School appropriateness is
crucial.
 Also write down what you think might happen if gravity
worked in a different way or if we were on a different planet.
BEFORE
 What is going through his mind and what might this look like on a different planet
or if gravity worked differently?
 Remember… School appropriate 
Songs by John Mayer, Sara
Bareilles, Pixie Lott, Coldplay, A
Perfect Circle
9.8 m/s2
Holds stuff down
A force that attracts objects
together
Increases as the mass of the two
objects increases
Decreases as the distance
between the two objects increases
 Newton discovered gravity
 Its always the same
 If you drop two objects
from different places, they
fall in parallel paths to the
ground
 The pull of planets and
stars will affect the
outcome of a persons life
based on their position in
the sky at the time of the
individual’s birth
 When we drop things they
fall down
 The Earth orbits around
the Sun
 The Sun moves around
the Milky Way
 Objects follow a trajectory
when launched at an
angle
 Your atoms stick together
 Newton’s Law of Universal
Gravity
 The nearer or more
massive 2 objects are, the
greater the force of
gravity between them
 F=G*((m1*m2)/d2)
 F is the force of attraction
 m1 and m2 are the masses
of the objects
 d is the distance between
the objects
 G is the gravitational
constant
 Not discovered by Sir Isaac
Newton
 Found by measuring the force
in Newtons between two
masses of 1 kg each, 1 meter
apart
 0.00000000006667 N*m2/kg2
Or
6.667 x 10 -11 N*m2/kg2
 This is a very weak force
 The crazy units make the end
result come out in Newtons
 How do you think this
machine works?
 Cavendish Torsion Bar Gravity
Balance
Used to make
exceptionally
large or
exceptionally
small numbers
more
manageable
If your starting
number is large,
you will have a
positive exponent
If your starting
number is small,
you will have a
negative exponent
Move the
decimal point so
that it causes the
number to be
greater than 1
and less than 10.
Example:
5,200,000.
Next, count the
number of times you
moved the decimal
point. This number
will become an
exponent.
5,200,000 = 5.2 x 106
0.0000314
3.14 x
-5
10
The exponent indicates which direction
the decimal moves
6.22 x 109
6,220,000,000
7.011 x 10-6
0.000007011
Linear speed - what we’ve already covered.
Speed in a line
Rotational speed - Number of revolutions per
minute
Tangential Speed – Speed of something moving
along a circular path
Centripetal Force – the force that causes an
object to travel in a circular path
Centrifugal Force – a force that moves directly
away from the center of a circular path
Lets demo!!!
Artificial Gravity – Can we make it?
How?
Are you really feeling gravity?
What force are you feeling?
When a quantity varies as the inverse square of
its distance from its source.
Ex: the book uses an example of a “butter gun”
Butter spray travels outward from the nozzle of the gun. Like gravity, the “strength of
the spray obeys an inverse square law.
1. What does the very small value of the gravitational constant, G, tell us about the
strength of gravitational forces?
2. What are the 2 masses and one distance that determine your weight?
3. Calculate the force of gravity on a 1-kg mass at Earth’s surface. The mass of
Earth is 6x1024 kg, and its radius is 6.4x106 m.
Gravitational Interactions
Gravitational Field- The type of force field that surrounds massive objects. (Such as
planets, moons, and stars)
• Near the surface of the Earth, the gravitational field strength is 9.8 N/kg or 9.8
m/s2.
• At the surface of Earth, the gravitational force on an object it the object’s weight.
Gravitational Interactions
To find acceleration due to gravity on any planet, use the following equation:
g=GM/R2
Where
G= gravitational constant, 6.67 x 10-11
M= mass of planet
R= radius of planet
Question:
How does g at the surface of Jupiter compare
with g at the surface of Earth?
Data: Jupiter’s mass is about 300 times that
of Earth, and its radius is 10 times greater
than the radius of Earth
Gravitational Field Inside a Planet
Full weight=mg
Full weight=mg
Half weight=
mg/2
• Gravitational fields exist inside
planets as well as around them.
• Acceleration, g, would decrease as
you moved toward the center of
Earth.
• At the center of Earth, your
acceleration would be 0 m/s2.
Why?
Center=
weightlessness
=
Ocean Tides
• Newton showed that tides are caused by
differences in the gravitational pull of the
moon on opposite sides of Earth.
• The moon’s attraction is stronger
on Earth’s oceans closer to the
moon, and weaker on oceans
farther from the moon.
• How can you explain this?
The earth also has atmospheric tides that occur in the ionosphere.
These produce electric currents that alter the magnetic field that surrounds
the Earth.
These “tides” regulate the degree to which cosmic rays penetrate into the
lower atmosphere.
This can account for subtle changes in the behaviors of living things.
They are greater when the atmosphere is having its spring tides. Near the full
and new moons.
The sun
 Two process
 1) Gravity pulling the star in
 2.) Fusion that blow solar material
outward.
When they balance we get a sun.
If the rate increases the sun gets bigger
If the rate decreases the sun gets smaller
When it runs out of fuel it becomes a red
giant and will be so big that it will swallow
Earth.
When the sun has burned all its fuel it will
no longer give off heat and become a black
dwarf.