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2017/18 8th, Unit 2

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Michelle Soporito

on 16 November 2018

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Transcript of 2017/18 8th, Unit 2

Unit 2: Gravity and Motion
Newton's
Law of Gravitation

a particle attracts every other particle in the universe using a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
The Universe
All of time and space and its contents
Anything and everything
Second Law of Motion
The acceleration of an object increases with increased force and decreases with increased mass
The Phases of the Moon
Earth's Tilt
The Planets
Quick Write:

What makes our planet so special that life develops? What makes it so different from the other planets of the solar system?

Here are
some extra assets :
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Newton's Three Laws of Motion
Sir Isaac Newton (1643-1727)
Physicist
Mathematician (creates calculus to prove theories)
Astronomer
Philosopher
Alchemist (early chemists)
Theologian
Topics
Newton's Laws of Motion
Newton's Law of Gravity
Gravity and the Universe
The Phases of the Moon

First Law of Motion (aka The Law of Inertia)
An object will remain at rest or in uniform motion in a straight line unless acted upon by an external force
Third Law of Motion
(aka Action and Reaction)
For every action there is an equal and opposite reaction.
Discovers/Creates:
Laws of Motion
Law of Gravity
Shape of the Earth
Optics (how light refracts and is viewed)
Law of Cooling
Inertia
The resistance of an object to change
*closely related to mass
The
heavier
the object is, the (
easier/harder
) it to move and the (
more/less
) inertia it has.
The
harder
it is to move, the
more
inertia it has
Is it easier to push empty or full boxes?
Is it easier to stop an empty or a full shopping cart?
Scene from "Gravity"
What parts of this clip are evidence of Newton's First Law of Motion?
Practical Application:
Seat belts
What happens when a car crashes?
The driver cannot compensate for the sudden forward force and continues to move forward because of their inertia.
If the driver wear a seat belt, the seat belt absorbs the unbalanced force and stops the driver from moving forward.
Sometimes seat belts are not enough to absorb the effects of the unbalanced force and air bags are deployed to cushion the impact
What happens if you do not wear a seat belt?
You are ejected from your seat at the same speed the car was moving before the crash. you will keep moving until another force (windshield, tree, ground) stops you.
The larger the force applied
The smaller the mass
the faster the object speeds up
Heavier
objects require (
more/less
) force to move the same distance as lighter objects?
More
Which has the lesser inertia?
Which can be moved more easily?
When net force is in the same direction as a moving object, the object moves in the same direction as the acting force
Remember force:
F=MA (force= mass x acceleration)
Centripetal force:
A force that moves an object in a circle
The force points towards the center of a circle
It changes and is always at a right angle to the objects motion
Without centripetal force, the object would move ina straight motion
Practical Application:
Spinning
When do the skaters seems to be spinning slower?
Faster?
Why?
The solar system works the same way as figure skaters. Planets closer to the center (the Sun) move faster that planets further away.
But remember, the solar system is constantly moving through space, so it looks a little different in motion.
Figure it out:
There are 2 Ferrari 488 Spider cars (red and blue). Both have the same engine (producing the same force) BUT the red car is made of lighter materials.
Which car will speed up faster and why?
The red because it has less mass
If the
same force
acts on two objects, the object with the
less mass
will have the (
greater/lesser
) acceleration.
Greater
What happens when an object loses mass while the force remains the same?
Quick Write
Example: The longer space craft fly in space, the more fuel it burns and the lighter it gets.
Answer: As the mass decreases, the acceleration increases (the spacecraft flies faster)
Action
Every time one object applies force on another object
Reaction
Second object applies force of equal size but in the opposite direction to the first object
Forces always act in pairs!
Quick Write
Summarize all three of Newton's Laws of Motion. Give an example for each other than what has been given in class.
OR
The natural pull of objects toward each other
All things in the universe are made of of matter
All matter is made up of atoms (also refereed to as particles) which are connected together
Each particle is attracted to every other particle in the universe
BUT
the closer the particles are, the stronger the attraction
the more mass something has, the stronger the gravitational force it has
Think back to 7th grade and remember:
Gravitational Equation:
Gravity on Earth
On Earth the strongest pull of gravity comes from the core of the planet, dense liquid metals.
All things on the surface are dragged toward the center of the Earth
If the Moon is affected by the gravity of Earth, why are astronauts not affected? Are they really weightless in space?
Quick Write:
What would happen if the Earth was hollow and you jumped through it? (Consider what you know of gravity, heat, speed, pressure, etc)
Galaxy
A gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter
Galaxies differ in shape
Different Types of Galaxies
Star
A luminous sphere of plasma held together by its own gravity
The closest star is our Sun
Quick Write:
Can a star die? What do you think would happen?
Yes, and its pretty dramatic
When it exhausts all its hydrogen it will turn into a white dwarf or a black hole
Our sun is set to expire in about 5 billion years and will then become a white dwarf
Moon
A permanent natural satellite
Many are called by names, ours has simply the title "The Moon."
Quick Write:
Why do you think some moons look so jagged? Why might Earth's moon not look the same?
Hyperion
Rhea
Moon
It actually does look the same, the Moon does not rotate in the sky, making one side not hit by outside elements. The moons have no magnetic field and thus get hit by asteroids and comets.
Asteroid
A small rocky body orbiting the sun, also considered a minor planet.
Comet
An icy small solar system body that, when passing close to the sun, heats up and begins to out gas, displaying a visible atmosphere or coma, and sometimes also a tail.
Meteor
The visible passage of a glowing meteoroid, comet or asteroid through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere, creating a streak of light via its rapid motion and sometimes also by shedding glowing material in its wake.
aka "Shooting Star"
Planet
A celestial body moving in an elliptical orbit around a star.
Has gravity crushing it into shape
Dwarf Planet
A planetary-mass object that is neither a planet nor a natural satellite
Can you imagine the actual size of the universe?
Galactic Definitions
Our galaxy is the Milky Way
Spiral shaped
Visible from Earth with low light pollution
Shines due to thermonuclear fusion at its core, converting hydrogen to helium
Causes massive explosions which work their way from the core to the outside, emitting massive amounts of heat and light
Our moon is the 5th largest in the solar system
Its gravitational pull affects the tides on Earth.

Some planets have many moons.
Ex. Jupiter has 67 known moons.
Large bodies past Jupiter are no longer considered asteroids

Mostly consist of minerals and rock

The main asteroid belt lies between Mars and Jupiter.

If the asteroid is smaller than 1 meter wide it is referred to as a meteoroid.
Mostly consist of ice, dust and rock particles

Two types:

Short period: Orbits the sun in less than 200 years
Possibly originate in the Kupiter Belt

Long Period: Orbits the sun every 200-thousands of years.
Possibly originate in the Oort Cloud
If it does not burn up on reentry and hits the ground it is then referred to as a meteorite.
If truly massive it is referred to as a fireball.
Can cause serious damage like in Russia 2013.
Can be different colors depending on content of the item entering the atmosphere
Orbits the sun

Has gravity to crush it into shape

*Has NOT cleared debris around its orbit
Hint:
4 major components

Atmosphere
Without this layer heat cannot be trapped and warm the planet
Provides gasses to breathe with
a layer of gases surrounding a planet or other material body, that is held in place by the gravity of that body
Temperature Range:
The hottest to the lowest temperatures recorded
Water Accessibility:
Water must be available and must be hydrogen based
If water is not available in liquid form, can it be found in solid or gas form?
Magnetic Field:
protect a planet from the charged particles streaming out from the Sun in the form of the solar wind.
Solar winds can blow everything off the surface of the earth
Atmosphere
Soil
Metallic cores in the planets create the magnetic field, creating "shields" which constantly break down and are reformed
Earth
Atmosphere
: Oxygen based
Due to plants/photosynthesis
Temp:
-128 F (-89c)-136F (58C)
Water:
Hydrogen based water and solid, liquid, gas
Magnetic Field:
Strongest in the solar system
Mercury
1st Planet from the Sun
Atmosphere
: Thin, made of Sodium, Magnesium, Calcium
3rd planet from the Sun
Temp:
-200F (-93c)- 375F (190C)
Water:
Ice on poles, not sure if hydrogen based
Magnetic Field:
Weak, destroyed by solar winds
Venus
2nd planet from the Sun
Atmosphere:
Carbon Dioxide based
Temp:
85F (30C)- 800F (127C)
Water:
Evidence of water in the past, blown off by solar wind
Magnetic Field:
none, the planet moves too slow
One of the only pictures of the surface of Venus. Surface pressure is 92x Earth. Landings only last about 23 minutes before they are crushed.
Quick Write:
Venus rotates in the opposite direction of Earth, it is the only planet in the solar system that does this. Why do you think this happens?
Scientists currently think in the beginning of our solar system a large asteroid hit Venus, knocking it off its axis and turning it upside down.
Mars
4th planet from the Sun
Atmosphere:
Carbon Dioxide based
Temp:
-220F (-140C)- 77F (25C)
Water:
Ice, hydrogen based but highly toxic
Magnetic Field:
None, giant asteroids disrupted the metal core, disrupting the field
Curiosity
Landed Aug 6,2012
Was only supposed to last 2 years, has lasted 5, still going strong
Took first images of Mars, made consideration of Mars as a colonizable planet possible
Jupiter
5th Planet from the Sun
Atmosphere
: 90% Hydrogen, ~10% Helium, it is the entire planet, there is no solid surface...
Temp
: -235F (145C)- 43,000F (24,000C)
Water
: Trace amounts as water vapor
Magnetic Field
: Largest in the Solar system
Saturn
6th Planet from the Sun
Water
: Trace amounts of water vapor in the atmosphere
Temp
: -255F (-178C)- 134F (57C)
Atmosphere
: 75% hydrogen, ~25% helium
Magnetic Field
: Second largest in the solar system
Uranus
7th planet from the Sun
Atmosphere
: ~82% Hydrogen, 15% Helium, 2% Methane (its what makes the planet blue)
Temp
: -370F (-218C) - -243F (-153C)
Water
: Ice core (Water/Methane/Ammonia), Large amounts of gas (Ice Planet)
Magnetic Field
: Moderate but weird, not centered on the poles
Neptune
8th Planet from the Sun
Atmosphere
: Hydrogen 80%, Helium 19%, Methane 1%
Water
: Ice mixed with rock in the core, trace amounts int atmosphere.
Water does not act like water does on Earth.
Temp
: ~-392F (-200C)
Magnetic Field
: Weird. Constantly rotating and changing, messes with everything we know about magnetic fields
How does Jupiter have a magnetic field when it has not metallic core?
Quick Write:
The pressure and heat in the core turn the gaseous hydrogen into metallic hydrogen
The planet moves fast, taking 9.9 hours to spin in one rotation (1 day)
The speed causes the metallic hydrogen to move quickly, creating the magnetic field
Juno
2011 Juno launches to orbit Jupiter and do scientific studies (it took 5 years to reach the planet). Currently it has circled the planet 8 times, sending back fabulous pictures
Red Eye
South Pole
North Pole
Cassini
2004 Cassini launched to orbit Saturn. Arrived in 1997, dived into the atmosphere 2017. Gave us the closest look at Saturn, its rings, and its moons
Hexagon storm
Rings and Rotation
Uranus is theorized to have been hit by 2 massive collisions, causing it to rotate to its side and in "reverse," much like Venus. It has very thin rings, which are hard to see with the naked eye.
Show until 6:37
Voyager
NASA launched 2 satellites in 1977 to explore interstellar space. Both swung by Jupiter and Saturn but only Voyager 2 went on to Uranus and Neptune. In 2012 Voyager 1 entered interstellar space, but it will still need ~30,000 years to get through the Oort Cloud.
The tilt causes the seasons of the Earth as we orbit the Sun
The Earth is tilted at 23.5 degrees from the Sun.
The Tides
The alternate rising and falling of the sea, usually twice in each lunar day at a particular place, due to the attraction of the moon and sun.
The Moon orbits the Earth, just as the Earth orbits the Sun
Called the Earth-Moon-Sun System
Eclipses
Solar Eclipse: When the Moon blocks the sunlight from the Earth
Lunar Eclipse: When the Earth blocks the sunlight from the Moon
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