Gravity and Tides

Gravity and Tides

8.ESS1.2

Announcements

-Grab the Gravity and Tides notes from Ms. Hansen

-You need your Ocean Tides Lab Sheet

Directions

READ each slide
WATCH each video
ANSWER each question
WRITE each note on your notes page

8.ESS1.2 - Explain the role of gravity in the formation of our sun
and planets. Extend this explanation to address gravity’s effect on
the motion of celestial objects in our solar system and Earth’s
ocean tides.

Learning Targets:

-Evaluate and explain the effect of gravity on the formation of stars
and planets.

-Construct an explanation about how gravity affects the motion of
celestial objects within the solar system.

-Use and develop a model of the effect of the gravitational force of
the moon on Earth’s oceans, and explain how the position of the
moon determines tide patterns, specifically spring and neap tides.

Gravity - What we know

• the attractive force between matter of all sizes

• affected by the mass and distance between all objects

• was the force that brought together bits of gas, dust, and rock leading to the formation of our solar system.

Gravity - What we will know soon!

Governs the motion of objects in the solar system which cause phenomena on Earth such as:

• Seasons

• Cycles of day and night

• Phases of the moon

• Tides

Gravity

Gravity, or gravitation, is one of the fundamental forces of the
Universe.

-holds the planets in orbit around the Sun

-keeps the Moon in orbit around Earth

-creates stars and planets by pulling all the material they are made of together

-allows the Moon to pull Earth's ocean water towards it, causing
the tides.

Gravity is the force
that PULLS objects
toward the CENTER

(not down).

Gravity - a force that pulls
objects to the center of mass.

For example, the Sun pulls
the Earth and all the planets to
the center of the Solar System.

The Earth also pulls you and
everything on it to the center.

Objects don't really fall "down"
they fall to the center.

Multiple Choice

Which phenomenon is a result of the gravitational force of the Sun?

• rotation of the planets on their axes

• rotation of the Moon on its axis

• revolution of the Moon around Earth

• revolution of the planets around the Sun

Gravitation is Affected By the Mass and Distance of Objects

Mass

Anything that has mass (made up of matter) also has gravity.

-Less mass = less gravitational pull

-More mass = more gravitational pull

Gravitation is Affected By the Mass and Distance of Objects

Distance

-Closer distance = more gravitational pull

-Further distance = less gravitational pull.

Multiple Select

What 2 key factors most affect the gravitational pull between 2 objects?

• Mass

• Inertia

• Weight

• Distance

• Velocity

Which graph accurately shows the relationship between

the mass of an object and its gravitational attraction?

Multiple Choice

From the slide before: Which graph accurately showed the relationship between the mass of an object and its gravitational attraction?

• A

• B

• C

• D

Multiple Choice

How would the gravitational force between the Earth and the Moon change if the Moon was twice as far away?

• The force would increase.

• The force would be the same.

• The force would decrease.

• The force would disappear.

Multiple Choice

Why does the Moon's gravity have a greater effect on Earth's tides compared to the Sun's gravity?

• The Sun is composed of mostly light gases such as Hydrogen and Helium

• The Sun's gravity only affects planetary orbits

• The Moon is much closer to Earth than the Sun

• The Moon is much less dense than the Sun

Planetary Orbits

Planetary orbits are caused by the pull of gravity.

The Sun’s gravitational attraction, along with the planet’s inertia
(continual forward motion), keeps the planets moving in elliptical orbits
(slightly oval) and determines how fast they orbit.

Multiple Select

What 2 key factors allow planets to orbit the Sun?

• Mass

• Weight

• Gravity

• Velocity

• Inertia

2 key factors that

allow planets to orbit

the Sun:

gravity and inertia.

Match

Match the following

• Newton's 1st Law

• Newton's 2nd Law

• Newton's 3rd Law

The Law of Inertia

Force = Mass x Acceleration

The Action Reaction Law

• The Law of Inertia

• Force = Mass x Acceleration

• The Action Reaction Law

Orbital Speeds

Look at the data

What information is this

data trying to tell us?

Orbital Speeds

-Planets closer to the Sun
orbit faster because the
gravitational attraction is
greater.

-Planets further from the
Sun orbit slower because
the gravitational attraction
is less.

Planets closer to the

Sun orbit faster.

Draw

1. Circle the Sun in RED.

2. Circle the 4 planets with the fastest orbital velocity in GREEN.

3. Circle the 5 planets with the slowest orbital velocity in ORANGE.

​A
B
C
D

Multiple Choice

Which answer choice on the slide before is correct?

• A

• B

• C

• D

Mass vs. Weight

Mass

Mass is a measure of the
amount of matter in an object.

Mass is a combination of the
total number of atoms, and the
type of atoms in an object.

An object's mass does not
change (unless you remove
some!)

Mass vs. Weight

Weight

An object's weight is a measure of the pull of gravity.

Weight CAN change depending on your location on Earth in the Solar
System, or in the Universe.

As you travel away from the Earth's surface, your mass stays the
same, but your weight reduces as gravitational pull decreases as you
go farther out into space.

Your weight changes depending on
where you are on Earth!

The gravitational pull of Earth on you can change slightly as you move
around the surface of the Earth because the Earth is not a perfect
sphere.

Your distance from Earth's center can change. Therefore, generally
speaking your weight is lower on top of a mountain than at sea level!

Why does your Weight Change in the Universe?

Your weight is a measure of the pull of gravity between you and the
body (planet) you are standing on.

Your weight depends on the gravitational pull of the celestial object.
So the greater the gravity greater your weight.

Notice the weight is so great on Jupiter due to its enormous mass!

Match

Match the following terms with their definition:

• Mass

• Weight

• Volume

• Velocity

how much matter is in an object

affect of gravity pulling on an object

how much space an object takes up

the speed and direction of an object

• how much matter is in an object

• affect of gravity pulling on an object

• how much space an object takes up

• the speed and direction of an object

Look Back at our Ocean Tides Student

Lab Data from Last Week!

Draw

1. Highlight in BLUE the number of high tides and low tides that occur each DAY.

2. Highlight in GREEN the two different types of tides that occur monthly based on the position of the Earth, Moon, and Sun.

3. Highlight in RED the four different moon phases mentioned in the reading.

Draw

COLOR a vertical block to fill in these days.

a. New Moon = Green

b. 1st Quarter = Yellow

c. Full Moon = Orange

d. 3rd/Last Quarter = Pink

COLOR and LABEL the moon phases using the hints below:

a. A new moon will have the highest high tides and the lowest low tides.

b. The quarter moon phases will have lower high tides and higher low tides than

normal.

c. A full moon will have the second highest high tides and the second lowest low

tides.

Open Ended

1. Looking at the graph, on what two set of dates did a spring tide occur?

Open Ended

2. In a complete sentence, describe the position of Earth, the Moon, and the Sun during a spring tide.

Open Ended

During a new moon phase the spring tide will have the highest high and lowest low tides. Why does the Moon and Sun being on the same side of Earth cause this to happen? (*Think about gravity and inertia)

Open Ended

3. Looking at the graph, on what two set of dates did a neap tide occur?

Open Ended

4. In a complete sentence, describe the position of Earth, the Moon, and the Sun during a neap tide.

Open Ended

Neap tides will have lower high tides and higher low tides. Explain why this happens. (*Think about gravity and inertia AND the position of the Sun, Earth, and Moon during this time. Why are a spring tide and neap tide different?)

Tides

Tides and planetary orbits are caused by the pull of gravity.

Tides are the rise and fall of the surface levels of Earth’s ocean water
caused by the gravitational effects of the Sun, and Moon on Earth.

Both the Sun and Moon Cause Earth's Tides!

Tides - caused by the gravitational pull of BOTH the Sun and Moon!

Different alignments of the Sun, Earth and Moon throughout the month
affect the tides experienced on Earth

Tides are predictable!

Multiple Select

Which 2 celestial objects are responsible for Earth's tides?

• Moon

• Milky Way

• Sun

• Mars

• Astroids

Tidal Bulges

As the Moon orbits Earth, the water
on Earth closest to the Moon
bulges out toward the Moon.

-The bulge = high tides

-Another high tide also occurs
on the opposite side of Earth.

-The area between the 2 high
tides = low tides

Notice Earth rotates into the the
high and low tides each day.

Draw

Draw a mini model of the Moon and Earth showing a tidal bulge occurring during high tide!

***Make sure you label your model!!

***Hint: you've seen a mini model of this recently if you were paying attention! :D

Why Do Tides Also Form on the Opposite side of
Earth from the Moon?

On the opposite side of the
Earth, the gravitational
attraction of the Moon is less
because it is farther away.

Inertia is greater than the
gravitational force, and the
water tries to keep going in a
straight line, moving away from
the Earth, also forming a bulge.

Why Do Tides Also Form on the Opposite side of
Earth from the Moon?

The gravitational attraction
between the Earth and the
Moon is strongest on the side of
the Earth that is facing the
Moon, simply because it is
closer.

This attraction causes the water
on this “near side” of Earth to
be pulled toward the Moon.

Open Ended

Why Do Tides Also Form on the Opposite side of Earth from the Moon?

Earth has 2 High Tides and 2 Low Tides Each Day

Earth rotates through two tidal “bulges”
every day so coastal areas experience
two high and two low tides every 24
hours and 50 minutes.

High tides occur 12 hours and 25 minutes
apart.

This occurs because the Moon revolves
around the Earth in the same direction
that the Earth is rotating on its axis.

2 high tides and 2 low tides every 24 hours

Open Ended

Explain why Earth has 2 high tides and 2 low tides every day.

Spring Tides

Occur when the Sun, Moon, and Earth are all in a line.

-New Moon = Moon is between the Sun and Earth

-Full Moon = Earth is between the Sun and Moon and Moon

During Spring tides the high tides are even higher and the low tides
are much lower.

-Spring tides create the greatest tidal difference in water levels
between high tide and low tides.

Spring tides are not high tides.

When the

gravitational effects
of the Sun and the
Moon combine, we

get spring tides,

which have nothing

to do with the
spring season.

The term "spring"

refers to the

action of the seas
springing out and

then springing

back.

Multiple Choice

Which of the following pictures is a Spring Tide?

Draw

Draw a simple model of Spring Tides that includes the following components and labels:

Moon, Earth, Sun, Tidal Bulge, High Tide, Low Tide, Full Moon, New Moon

Which of the lines represent a Spring Tide?

Multiple Choice

Which line represents a Spring Tide?

• Red

• Blue

• Green

• Purple

Neap Tides

Occur when the Sun and Moon are at right angles to each other

-Moon Phases = 1st and 3rd (last) Quarter

-the Sun and Moon are pulling on Earth in two different directions causing
lower high tides and higher low tides to be experienced on Earth.

-Neap tides create the smallest tidal difference in water levels between the
high tide and low tides.

Neap tides are not low tides.

Neap tides occur
approximately 2
times each month
during the First and
Last Quarter Moon

Phases.

Multiple Choice

Which diagram represents the alignment of the Earth, Moon, and Sun during a neap tide?

Draw

Draw a simple model of Neap Tides that includes the following components and labels:

Moon, Earth, Sun, Tidal Bulge, High Tide, Low Tide, 1st Quarter Moon, 3rd Quarter Moon

When the Sun and Moon are at right angles to each other and their
tidal influences partially cancel each other out, neap tides occur, and
the tidal difference between high and low tide is the smallest.

The term "neap" means without the power.

Because the oceans take a bit of time to catch up to the Moon,
spring and neap tides usually occur about a day after the
respective lunar phase.

Which of the lines represent a Neap Tide?

Multiple Choice

Which line represents a Neap Tide?

• Red

• Blue

• Green

• Purple

Spring and Neap in Action

• The animation below shows the revolution of the moon and spring vs. neap tides.

Multiple Choice

Which arrangement of the Sun, Earth, and Moon would produce the highest high-tides and the lowest low-tides on Earth?

• A

• B

• C

• D

Multiple Choice

What effect will the positions of the Moon have on Earth’s tides?

• A

• B

• C

• D

Multiple Choice

Which positions of the Moon will correspond to spring tides?

• A

• B

• C

• D

Labelling

Spring and Neap Tide Simple Model

The ocean’s tides are caused mainly by the gravitational effects of the moon, but also by the sun to a lesser degree. 

When the Earth, moon, and sun are aligned, the overall gravitational pull is the greatest and causes the largest tides: spring tides. 

When the Earth, moon and sun are at right angles, the pull is minimized and causes the weakest tides: neap tides. 

Add the labels below to the diagram:

Drag labels to their correct position on the image

neap tides

moon

spring tides

low tide

high tide

sun

earth

Multiple Choice

Did you complete all the red and underlined portions of your hand written notes while going through this self-guided Quizziz?

• Yes

• No

Poll

Have you finished your Celestial Objects Book?

• Yes

• No

Poll

Do you have any "ungraded" assignments in Aspen you need to complete?

• Yes

• No