GRAVITY
MS-ESS1-2 Develop and use a model to describe the role of gravity in the motions within galaxies and the solar system.
MS-PS2-4 Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects.
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GRAVITY VOCAB
An attractive force that exists between any objects that have mass, that pulls them together.
GRAVITY:
MASS:
WEIGHT:
The amount of matter/atoms in an object.
The pull of gravity on an object’s mass. (how “heavy” something is)
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Mass vs. Weight
An object will always have MASS.
(Mass is indestructible. The amount of ATOMS in that object doesn’t change due to the pull of gravity.)
An object’s WEIGHT is the measure of the strength of gravity pulling on its mass.
(The amount of FORCE on an object can change due to its location.)
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Mass vs. Weight… In Space!
Watch up to 4:05
How Does Gravity Hold Our Solar System Together?
The forces at work on the tennis ball:
The string pulls inward
The ball pulls outward
What happens if you cut the string?
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Gravity’s Role in Our Solar System
Gravity is the force that keeps planets and moons in orderly orbit in our solar system.
E
The Sun pulls inward
The Earth pulls outward
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Think about it: If both objects didn’t pull back against the other, what would happen?
Honors Students ONLY:
Click into this slideshow to add additional info on Gravity calculations to your notes
Gravity: Two Variables
The strength of gravity is determined by two variables:
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How does gravity affect Motions in our solar system?
Mercury
Jupiter
Small mass, small force of gravity (objects weigh less when on Mercury)
Close to sun, so has fast orbit due to strong pull rom the Sun (88 days).
Large mass, large force (objects weigh much more when on Jupiter)
Far from sun, so has slower orbit due to weaker pull from the Sun (12 Earth years or 4,383 days).
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How does gravity affect motions in our solar system?
Mercury
Jupiter
Close to sun, so has short orbital period (fast orbit)
(88 days).
Far from sun, so has long orbital period (slower orbit)
(12 Earth years
OR 4,383 days).
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EARTH
Mercury
to
If you travelled from:
How will the strength of gravity change?
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The force of gravity is now.... | WEAKER than Earth’s | |
Your weight would be... | LESS ↓ | |
Why? | Because Mercury’s smaller mass cannot pull on you as hard! | |
Trip: Earth to Mercury
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Saturn
Mercury
to
If you travelled from:
How does the strength of gravity change?
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The force of gravity is now.... | You’ve already completed this section. | STRONGER than Mercury’s |
Your weight would be... | MORE ↑ | |
Why? | Because Saturn’s larger mass pulls down on you harder! |
Trip: Earth to Mercury
Trip: Mercury to Saturn
As the mass of the object you are
interacting with increases ↑…
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The force of gravity increases ↑
Earth
If you travelled far from Earth:
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How does the strength of gravity change?
The force of gravity will be.... | WEAKER as you move FARTHER away | STRONGER as you move CLOSER |
Your weight would be... | LESS ↓ | MORE↑ |
Why? | Because the distance to the object pulling on you is increasing | Because the distance to the object pulling on you is decreasing |
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Distance Travelled From an object
As distance between objects increases ↑…
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The force of gravity decreases ↓
As distance between objects decreases ↓ …
The force of gravity increases ↑
(and so obviously…)
BIG IDEAS about GRAVITY!
Force of gravity & MASS
have a
DIRECT RELATIONSHIP
As the mass of an object in a force pair INCREASES, the force of gravity INCREASES.
Force of gravity & DISTANCE
have a
INVERSE RELATIONSHIP
As the distance between two objects INCREASES, the force of gravity DECREASES.
mass
gravity
distance
gravity
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Honors Students- Stop Here!
Gravity Review HW
Gravity Review HW
Gravity Review HW
Gravity Review HW
Gravity Review HW
Why do we
fall DOWN?
our masses pull on each other…
but the Earth “wins” because it is MORE MASSIVE.
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Refresher: What is Weight?
Refresher: What is Gravity?
Weight is the measure of the PULL OF GRAVITY on any object (mass.)
Gravity is an attractive force that pull objects with mass together.
Things do not need to touch to feel the pull of gravity.
Without GRAVITY, an object will not have WEIGHT, but it will always have MASS << the amount of atoms in an object.
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What is a gravitational Ratio?
Mass of Planet
Mass of Earth
divided by
That planet’s gravitational ratio
A comparison of the strength of a planet’s gravity to Earth’s gravity.
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Refresher: What is Gravity?
Gravity Lab
Gravity Lab
Gravity Lab
Gravity Lab: “What’s Pulling on Me?” Analysis Questions
[All Analysis questions must be answered in COMPLETE sentences, in YOUR OWN WORDS (academic integrity).]
Gravity Lab: Part 2
Gravity Lab
What would happen if gravity stopped?
Misconceptions
(higher level video)
Discusses why people think they fall the same, why they think force on them is equal
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