TN 8.PS2.3-MASTER

​8.PS2-3-Topic 1
Understanding Gravity as Force

By Jessica Freeman

Students will explain gravity as a universal attractive force acting between all objects with mass.

​

​Topic 1
Objective

​ mass

​ towards

​ closer

​ farther

​ orbit

​ Earth

Objective: By the end of this lesson, students will understand the basic concept of gravity, its effects on everyday life, and how it keeps celestial bodies in orbit.

​What is

Earth has gravity because it has mass, and gravity pulls everything towards its center. This is why objects fall when you drop them.

The Difference Between Mass and Weight

​The Force of Gravity is Influenced By Both the Mass and Distance of Objects

​Mass

• Anything that has mass (made up of matter) also has gravity. Less massive objects have a weaker gravitational pull.

• More massive objects have a greater gravitational pull (such as the Sun).

​Distance

• The closer the distance between objects, the greater the gravitational pull.

• The farther the distance between objects, the weaker the gravitational pull.

Gravity (A Universal Force)

Isaac Newton

Isaac Newton had a lot of brilliant ideas in his lifetime and a massive one was universal gravitation. Universal gravitation is not just the fact that objects on earth fall to the ground. His big idea was that all objects in the universe attract all other objects.

For example, not only does the Earth use its gravity to pull the moon towards it, the moon also pulls on the Earth causing it to be slightly displaced.

Newton's Law of Universal Gravitation

Any object with mass is attracted to any other object with mass.

The amount of force depends on distance and the amount of mass of the object.

Newton realized that both the apple and moon are really falling. The only difference is that the moon has inertia, and the apple doesn't.

What is inertia?

Inertia is the resistance of any physical object to any change in its velocity

Inertia

While the apple is falling from a still position in the tree, the moon has a constant velocity.

Normally the moon would move forward in a straight line at a constant velocity, through space. But because of gravity, the moon is attracted to the earth, making it fall towards it. This inertia, or the moon's resistance to being pulled into the Earth, is what keeps it orbiting.

The moon acts like a projectile with its inertia taking it forward as it also falls to the earth. This combined action keeps the moon in orbit around the earth.

This is why an object on earth falls to the ground while the moon continues in its circular path.

​8.PS2-3-Topic 2
Mass & Gravitational Strenth

By Jessica Freeman

Students will describe how the mass of an object affects the strength of its gravitational pull.

​

​Topic 2
Objective

stronger

stronger

matter

Open Ended

What do you think keeps the Earth in orbit?

Multiple Select

Which are true about mass? (hint: 2 answers)

• Mass is a measure gravity

• Mass cannot change

• • Mass is what kind of atoms something is made of

• • Mass is what shape it is

Multiple Select

Which are true about weight? (hint: 2 answers)

• • Weight is how heavy something is

• • Weight is caused by gravity

• • Weight is the shape of an object

Multiple Select

The strength of gravity depends on ________________________________ and their ______________________________.

• the mass of the objects

• the weight of the object

• distance from one another

• the shape of the object

Open Ended

Why do you think we weight different on each planet?

Draw

Gravity and inertia keep the moon in orbit around Earth. Complete the diagram by drawing an arrow to indicate the force of gravity Earth exerts on the moon as it orbits Earth.

Gravity is...

A force of attraction between objects due to their masses.

• Gravity exists between objects even when they are not touching.

• Gravity is a non-contact force.

• It is an attractive force because it always pulls objects toward each other.

​Do you think this dog has ever studied gravity? He sure seems to know that the ball is going to fall - and where it is going to land!

Every object in the universe attracts every other object with a gravitational force.

The strength of the force depends on two things: mass and distance.

Multiple Choice

If an objects mass decreases, the force of gravity

• increases

• decreases

Multiple Choice

If an objects mass increases, the force of gravity

• increases

• decreases

Multiple Choice

If the distance between two objects increases, the force of gravity

• increases

• decreases

Multiple Choice

If the distance between two objects decreases, the force of gravity

• increases

• decreases

Draw

Draw the force arrows to model each scenario correctly.

Multiple Choice

A metal ball sits motionless on a flat surface. Which of these would make the ball move?

• The force of gravity becomes less.

• The force of gravity becomes greater.

• Two equal horizontal opposing forces act upon the ball.

• Two unequal horizontal opposing forces act upon the ball.

Multiple Choice

What is gravity?

• a contact force

• a frictional force

• a magnetic force

• a noncontact force

Multiple Choice

Which of these is considered a contact force?

• the force between two magnets

• the friction between an object and air

• the gravitational pull of a planet

•      the force between two charged particles

Multiple Choice

Why is the friction force considered to be a contact force?

• Friction affects only solid objects.

• Friction always acts in the same direction.

• Friction is produced when objects slide past one another.

• Friction acts in a direction opposite to the direction of an object’s motion.

Multiple Choice

Which of these describes the gravitational force from a planet?

• large and pulls objects toward itself

• small and pulls objects toward itself

• large and pushes objects away from itself

• small and pushes objects away from itself

Multiple Choice

Which pair of objects has the largest gravitational force?

• marble and car

• marble and baseball

• car and bowling ball

• There is no gravitational force between any of these pairs of objects.

Multiple Choice

True or False An elephant has more mass than a penny.

• True

• False

Multiple Choice

True or False An elephant and a penny will have the same force of gravity acting on them.

• true

• false

Multiple Choice

True or False A free falling elephant will accelerate faster than a penny.

• true

• false

​8.PS2-3-Topic 3
Distance & Graviational Strength

By Jessica Freeman

Students will explain how the distance between two objects affects the strength of gravity.

​Topic 3
Objective

​weaker

​weaker

​closer

​The Force of Gravity is Influenced By Both the Mass and Distance of Objects

​Mass

• Anything that has mass (made up of matter) also has gravity. Less massive objects have a weaker gravitational pull.

• More massive objects have a greater gravitational pull (such as the Sun).

​Distance

• The closer the distance between objects, the greater the gravitational pull.

• The farther the distance between objects, the weaker the gravitational pull.

Multiple Choice

When placed at equal distances apart, the greatest gravitational attraction will be between two

• skateboards

• bowling balls

• school buses

Multiple Choice

What are Noncontact Forces?

• Objects fall to the ground because Earth exerts an attractive force on them.

• is an attractive force that exists between all objects that have mass

• force that one object can apply to another object without touching

• a region of space that has a physical quantity (such as a force) at every point

Multiple Choice

What is Gravity?

• A force that one object can apply to another object without touching

• is an attractive force that exists between all objects that have mass

• Objects fall to the ground because Earth exerts an attractive force on them

• a region of space that has a physical quantity (such as a force) at every point

Multiple Choice

When the mass of one or both objects……., the gravitational force between them also ……….

• A. Decrees, increases

• B. increases, decrees

• C. increases, increases

• D. Decrees, decrees

Multiple Choice

What is mass?

• Your weight on Earth.

• How much matter in an object?

• A push or pull.

• The same thing as your weight.

Multiple Choice

Who is this?

• Isaac Newton

• An old dude

• Keppler

• No idea

Multiple Choice

Which is needed to determine the amount of gravitational force between two objects?

• distance and mass

• weight and time

• area and weight

Multiple Choice

The gravitational force exerted by an object depends on its

• volume

• mass

• weight

Multiple Choice

as the mass of an object increases, the pull of gravity...

• Increases

• Decreases

• Stays the same

Multiple Choice

Why do we have a stronger gravitational attraction with Earth than the Sun?

• the sun has a larger mass

• the Earth has a larger mass

• we are closer to center of sun

• we are closer to center of Earth

Multiple Choice

What does the strength of gravity between two objects depend upon?

• Mass & distance
• Mass & weight
• Gravity & inertia
• Inertia & mass

Multiple Choice

________is what makes up all things in the universe.

• Weight

• Mass

Multiple Choice

The gravitational force between two objects changes with the distance between the two objects

• True

• False

Multiple Choice

An object with more mass will exert greater gravitational force than an object with lesser mass.

• True

• False

Gravity

The force of attraction between all objects in the universe

Gravity

Gravity is only significant when one of the objects is very large, like the Earth. There is very, very little gravitational attraction between you and your couch – but there is some! 

Poll

What makes an object have stronger gravitational pull?

• it's size: if the object is large

• it's distance from another object

• it's mass: if it's heavier

Gravity increases as mass & size increases

Poll

As the mass of the objects DECREASES, gravity will...

• increase

• decrease

• stay the same

Multiple Choice

If the distance between object DECREASES and gets closer together, the force of gravity...

• increase

• decrease

• stay the same

Orbit

The path of a celestial body (such as a moon or a planet) around another body.

Orbital velocity

The speed an object must travel to achieve a perfectly circular orbit

Escape velocity

The speed an object must travel to escape the gravitational pull of a planet.

If an object is launched at escape velocity, it will leave the planet and not return.

Trajectory

The path of an object through space. 

Multiple Choice

1. The Earth has more mass, so it has a gravitational pull on the Moon, but the Moon doesn't have a gravitational pull on Earth.

• TRUE

• FALSE

False!

Earth pulls on the Moon and the Moon pulls on the Earth! Newtons' Law of Universal Gravitation says that all objects in the universe attract all other objects! See how the moon slightly pulls on the Earth, throwing it off-center!

Multiple Choice

Tides are the cycle of rising and falling ocean water that repeats automatically every

• 24 hours
• 12.5 hours
• 25 hours
• 6.25 hours

Multiple Choice

Differences in the moon's and sun's pull on different sides of the Earth cause _________.

• gravity
• lunar phases
• tides
• dabbing

Multiple Choice

Which body has the greater effect on Earth's tides?

• Sun

• Saturn

• Moon

• Venus

Multiple Choice

What is a difference between spring and neap tides?

• Spring tides occur when the earth and sun are IN LINE with the new or full moon.

• Spring tides occur when moon in 3rd or 1st quarter phases

• Spring tides are LOWER than neap tides

• Spring tides occur in Spring and neap tides can occur in any season

Multiple Choice

What type of tides would this arrangement of earth-moon-sun create?

• neap tide
• spring tide
• new moon tide
• full moon tide

Multiple Choice

The diagram below shows the alignment of the sun, the moon, and Earth. In which locations are neap tides taking place?

• 1 and 2

• 1 and 3

• 2 and 4

• 3 and 4

Spring Tides

• Spring tides occur when the Earth, the sun, and the moon are in a line. The name spring tide has nothing to do with the season.

• Spring tides occur during the full moon and the new moon.

• These are very strong tides and occur every 14 days.

• The diagrams below show the two situations in which spring tides occur.

Multiple Choice

When do spring tides occur

• New moon

• Full moon

• Both

Neap Tides

• Neap tides which are very weak tides, occur during this time.

• During this time, the gravitational forces of the moon and sun are perpendicular to each other which cause the pulls to "cancel out" each other.

• The diagrams below show the two situations in which neap tides occur.

Multiple Choice

Are neap tides weak or strong

• Strong

• Weak

Spring and Neap in Action

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

Multiple Choice

Look at the picture and answer below.

• f

• g

• h

• j

▶ Very High Tides

▶ Nothing to do with Spring

▶ Occur with the sun, moon,

and earth are in a line

▶ Occur during a new moon

(we see no moon) and a full
moon

Types of tides

Spring Tide

▶ Low tides are higher and

High tides are lower

▶ Occur with the sun and

moon are at a right angle

▶ Occur during the quarter

moons (when we see half
of the moon)

Types of tides

Neap Tide

Multiple Choice

The tidal bulge follows the movement of the _____.

• moon

• sun

• Earth

• ocean

Multiple Choice

When the moon is at full moon or new moon, what type of tide will we experience?

• rip tide
• spring tide
• neap tide
• breaker tide

Multiple Choice

What type of tides would this arrangement of earth-moon-sun create?

• neap tide
• spring tide
• new moon tide
• full moon tide

Multiple Choice

What happens when there is a spring tide

• high tides 
• really high tides
• low tides

Multiple Choice

Wha type of tide would this arrangement of earth-moon-sun create?

• full moon tide

• new moon tide

• neap tide

• spring tide

Multiple Choice

How many low tides and high tides happen in a day?

• 1 low tide, 1 high tide
• 4 low tides, 4 high tides
• 3 low tides, 3 high tides
• 2 low tides, 2 high tides

Multiple Choice

When the Sun, Moon and Earth are aligned in this way, which type of tide will Earth have?

• Spring

• Neap

• Summer

• Winter

Multiple Choice

The diagram below shows the alignment of the sun, the moon, and Earth. In which locations are neap tides taking place?

• 1 and 2
• 1 and 3
• 2 and 4
• 3 and 4

Multiple Choice

A new moon results in a ____ Tide

• Neap
• Spring
• Neither

Multiple Choice

A full moon results in a ____ Tide

• Neap
• Spring
• Neither

Multiple Choice

A Last Quarter moon results in a ____ Tide

• Neap
• Spring
• Neither

The mass of the object, and the distance the object is from another object.

In this picture, the arrows show the strength of the gravity. The arrows get longer when mass increases, and smaller when distance increases.

Multiple Choice

3. Which planet does the Sun have the least amount of gravitational force towards.

• Earth

• Venus

• Saturn

• Neptune

Neptune is the farthest away, so the distance between the objects is greater. As distance increases, gravity decreases.

Open Ended

4. Give an example of inertia, in your own words. HINT: Anything that shows a resistance to any change in an objects velocity.

Multiple Choice

5. The direction the moon travels in while orbiting the Earth is in a circular path.

• True

• False

FALSE! The moon is actually traveling in a straight line, at a constant speed & velocity.

Earth's gravity attempts to pull the moon in, but the moon is traveling too fast (it has inertia), so it continues in this orbit at a constant velocity.

​8.PS2-3-Topic 4
Gravitational Interactions in the Solare System and Galaxies

By Jessica Freeman

Students will analyze examples of graviational interactions (Earth and Moon, Sun and Planets, stars in galaxies) and construct arguments with evidence to support claims.

​Topic 4
Objective

​Sun

​Tides

​gravity

​Moons

Gravity Part 2

Effects of Mass & Distance on Gravitational Force

• The more massive an object, the greater it's gravitational pull

• The closer the distance between objects, the greater the gravitational pull
  

• The gravitational pull between the Sun and each planet or between Earth and it's moon causes distinct motions between and among the objects

Multiple Select

If the mass of an object increases, what happens to the gravitational pull?

• Increases

• Decreases

Multiple Select

The closer that two objects come together, what happens to the gravitational pull?

• Decreases

• Increases

Effects of Gravity on Planetary Orbits

• The Sun's gravitational attraction along with a planet's inertia (continued forward motion), keeps the planets moving in an elliptical orbit (slightly oval) & determines how fast they move.

Effects of Gravity on Planetary Orbits

• Planets nearer to the Sun move/orbit faster due to the higher gravitational pull from the Sun.

• Planets farther from the Sun move/orbit slower due to the gravitational pull becoming less the farther from the Sun a planet is located.

Mercury, Venus, Earth, Mars

4 planets closest to the Sun that orbit faster because of higher gravitational pull between them and the Sun

Jupiter, Saturn, Uranus, Neptune

Even though these 4 planets are more massive, the large distance that they are from the Sun reduces the gravitational pull the Sun has on them.

Multiple Choice

Inertia is:

• Forward motion

• Reverse motion

• Sideways motion

Multiple Choice

Planets closer to the sun have:

• More gravitational pull with the Sun

• Less gravitation pull with the sun

Multiple Choice

What keeps planets in elliptical orbits?

• Gravitational attraction

• Inertia

• Both gravitational attraction & inertia

• Neither one

Gravity and Planetary Motion

Issac Newton

Newton's Law of Universal Gravitation states that every particle attracts every other particle in the universe with force directly proportional to the product of the masses and inversely proportional to the square of the distance between them.

Answer the questions on the slides after the simulation.

​

Experiment with Mass and distance using the Phet simulation.

Multiple Choice

The bigger an object is, the smaller the force of gravity

• True

• False

Multiple Choice

As one object gets closer to another object, the force of gravity will increase.

• True

• False

Multiple Select

Which variables affect gravity?

• Weight

• Mass

• Distance

• Density

• Speed

​Orbital motion occurs whenever an object is moving forward and at the same time is pulled by gravity toward another object.

How gravity affects orbits

is the motion of planetary bodies moving forward while being dragged by gravity toward another body.!

Orbital motion

Multiple Choice

What is true about the distance between a planet and the sun and the planet’s revolution around the Sun?

• The closer the planet is to the sun, the slower it orbits.

• The farther the planet is to the sun, the faster it orbits.

• The farther the planet is to the sun, the brighter the sun is.

• 
  The closer the planet is to the sun, the faster it orbits.

Multiple Choice

A(n) _____ is the curved path of an object around a point/object in space.

• revolution

• orbit

• rotation

• phase

Multiple Choice

A planet with a large orbit has...

• a short day

• a long year

• a long day

• a short year

Multiple Choice

Without gravity, the stars, planets and all objects in the universe would _______.

• move in a straight line

• move in a random direction

• stop moving

• continue to orbit each other

Multiple Choice

What would happen to Earth if the Sun's gravity disappeared?

• Earth would move toward the Sun and eventually crash into it.

• Earth would sit motionless and not moving.

• Earth would drift off in space because nothing would hold it in the Solar System.

• Earth would continue to orbit in our Solar System normally.

Multiple Choice

Here is a model of the gravitational force of Mars. Objects A and B have the same mass but are different distances from Mars. Which statement explains how the gravitational force affects the two objects?

• Object A and B will be affected equally by the gravitational force.

• Object B will be more affected by the gravitational force because it is closer to Mars than Object A.

• Object A will be more affected by the gravitational force because it is farther from Mars than Object B.

Inertia

While the apple is falling from a still position in the tree, the moon has a constant velocity.

Normally the moon would move forward in a straight line at a constant velocity, through space. But because of gravity, the moon is attracted to the earth, making it fall towards it. This inertia, or the moon's resistance to being pulled into the Earth, is what keeps it orbiting.

The moon acts like a projectile with its inertia taking it forward as it also falls to the earth. This combined action keeps the moon in orbit around the earth.

This is why an object on earth falls to the ground while the moon continues in its circular path.

Gravity in Our Solar System 1:

Gravity Variables

Objective: I will be able to explain how mass and distance affect the force of gravity between two solar system bodies.

Variable 1: Mass

• If the less mass the objects have, the weaker the gravity will be between them.

• The more mass the objects have, the greater the gravity between them.

Multiple Choice

The ________ mass two objects have, the greater the gravity between them.

• more

• less

Multiple Choice

Which two objects would have a stronger gravitational attraction?

Multiple Choice

When a person drops a ball, it is attracted to the ground. Which statement best explains why the ball falls to the ground?

• The Earth has more mass than the person. The strength of gravity is stronger between the ball and the Earth.

• The Earth has more mass than the person. The strength of gravity is stronger between the person and the ball.

Variable 2: Distance

• The closer objects are, the stronger the gravity is between them.

• The farther apart objects are, the weaker the gravity is between them.

Multiple Choice

Gravity is weaker if objects are _____________.

• closer together

• farther apart

Multiple Choice

Which two objects would have a stronger gravitational attraction?

Multiple Choice

Which object will experience the weakest gravitational pull towards Object X?

• Object A

• Object B

• Object C

Open Ended

Base your answer to the following question on what you know about distance and gravity and the information in provided in the table.

Why does the Moon orbit the Earth and not the Sun?

Check your answer by clicking the play button below!

Multiple Choice

Force of gravity is directly proportional to

• Mass
• Weight
• Distance
• Time

Multiple Choice

Two factors effecting the magnitude of the force of gravity between 2 objects are...

• mass and distance 
• mass and matter
• distance and weight 
• weight and mass