1. It’s a phenomenon, it’s a force, it’s the fabric of space and time …
Gravity
It’s a phenomenon, it’s a force, it’s the fabric of space and time …
PART 1-A: A Historical Look at Gravity

2. I CAN explain how our understanding of gravity evolved throughout early history. This means I can explain how the work of men like Aristotle, Galileo, and Copernicus built the foundation for what we now know about the force of gravity.

3. What do you already know about gravity?
With your seat or elbow partner divide a scrap sheet of paper into 3 sections and
write down the following:
1. What do you know about gravity that are facts?
2. What do you think you know but are a little fuzzy about whether it is fact or not?
3. What don’t you understand at all about gravity?
When you and your partner have come to a consensus, record your statements neatly onto post-it notes
Be ready to share out with the class
in 15 minutes.

4. Historically what we know about gravity began with our ancestor’s fascination with the heavens …

5. To understand where we’re going in science, we often have to know where we’ve been. A look back activity …
You are going to be placed in teams of 2, 3 or 4.
Each of you will read a short article on a historical figure in science who impacted our understanding of gravity.
While you read, underline places in the text that relates to gravity. It may not explicitly say “gravity” but the phenomenon must be directly or indirectly related to gravity. In other words, the scientist may not have known that what they were making scientific statements about was gravity.
Once you’ve read your article, share out with your partners.
You have 10 minutes.

6. Making meaning of what you have read with your partners…
With your partners, share your notes that are directly related to your scientist’s contribution to our understanding of gravity. (even if they did not know it was gravity)
Rewrite these notes on a scrape sheet of paper together in your own words. Summarize long sections when necessary.
You have minutes.

7. QUICK WRITE DEBRIEFING
READ over the notes that you have made on your scientist. Using a graphic organizer, compare how your scientist understood gravity back then with how you said on your post-its that you understand gravity now. What are the similarities and what are the differences?

8. It’s a phenomenon, it’s a force, it’s the fabric of space and time …
Gravity
It’s a phenomenon, it’s a force, it’s the fabric of space and time …
PART 1-B: A Historical Look at Gravity
SHARING OUR UNDERSTANING OF GRAVITY THROUGH THE DISCOVERIES AND CONTRIBUTIONS OF DIFFERENT SCIENTISTS

9. I CAN explain how our understanding of gravity evolved throughout early history. This means I can explain how the work of men like Aristotle, Galileo, and Copernicus built the foundation for what we now know about the force of gravity.

10. Let’s revisit our “quick write” from yesterday …
Let’s share out and see if we share some of the same ideas with our scientists and if some of our own understanding surpasses that of our early scientists.
verses

11. Now you’re ready to share what you have learned in your article with your fellow students
Along with your partners, create a “mini” poster of your findings directly related to your scientist’s contribution to our understanding of gravity. (even if they did not know it was gravity)
Remember, the findings you put on your poster should be in your own words!
Be ready to share out with the class by readying your poster for a gallery walk.
You have 10 minutes.

12. During your gallery walk make notes on each of the scientists and their contributions to our understanding of gravity.

13. It’s a phenomenon, it’s a force, it’s the fabric of space and time …
Gravity
It’s a phenomenon, it’s a force, it’s the fabric of space and time …
PART 1-C: A Historical Look at Gravity
ENHANCING OUR UNDERSTANDING OF GRAVITY THROUGH THE CREATION OF A HISTORICAL TIMELINE

14. I CAN explain how our understanding of gravity evolved throughout early history. This means I can create a historical timeline explaining how the work of men like Aristotle, Galileo, and Copernicus built the foundation for what we now know about the force of gravity.

15. Create a Historic Timeline Comic Strip
With your notes, create a historic comic strip on the scientists from your gallery walk
Be sure your illustrations depict their contributions to our understanding of gravity
Through additional research, add something interesting about each of the scientists that can add humor to your comic
Be sure your comic strip forms a timeline as well

16. Create a Historic Timeline
With your notes, create a historic timeline on the scientists from your gallery walk notes.
Be sure your timeline includes their contributions to our understanding of gravity
Add your pictures from your notes to symbolize their contribution.

17. Let’s share our timelines!
An early history of our understanding of gravity
verses
Geocentric
Heliocentric

18. State of Physics- Newton and His Laws
By now the world knew:
Bodies of different weights fall at the same speed
Bodies in motion did not necessarily come to rest
Moons could orbit different planets
Planets moved around the Sun in ellipses with the Sun at one focus (Kepler’s 1st law)
The orbital speeds of the planets obeyed Kepler’s 2nd and 3rd laws
But why??? Isaac Newton put it all together.

19. Newton’s Concepts m (mass): How much stuff something contains
v (velocity): A body’s speed and direction
3) a (acceleration): The change in a body’s velocity
4) F (force): What is needed to change a body’s velocity

20. Newton’s Laws of Motion
A body’s velocity will remain constant, unless acted upon by an outside force = inertia

21. Newton’s Laws of Motion
A body in motion will remain constant, unless acted upon by an outside force = inertia
A body’s acceleration depends on the force acting upon it, and will be in the direction of that force. Its resistance to acceleration depends on its mass. In equation form, this is
F = m a
For every force, there is an equal and opposite force.

22. Newton’s Law of Gravity
There is an attractive force between two bodies called gravity. The force of gravity depends on the masses of the two bodies, and their separation (squared); the larger the mass, the greater the attraction; the larger the separation, the smaller the attraction.
G m1 m2
Basically, this means that the 2 most important factors that affect gravity are Mass and Distance.
F = 
r 2

23. Example of Gravity – a Thrown Ball
When you throw a ball, there are 2 motions: horizontal & vertical.
The horizontal motion obeys Newton’s first law (bodies in motion will stay in motion). The attractive force of gravity causes the upward motion to decelerate, and then change direction. You see the composite of the two behaviors.

24. Example of Gravity – a Thrown Ball

25. Example of Gravity – Weightlessness
You feel weight because of Newton’s third law. Gravity is pulling you down, but the ground is not allowing you to fall. It must therefore be exerting a force on you to keep you from falling. That force is the weight that you feel.
If you were allowed to fall, you would not feel any weight. So when you are in free-fall, you feel weightlessness.

26. Example of Gravity – Weightlessness
You feel weight because of Newton’s third law. Gravity is pulling you down, but the ground is not allowing you to fall. It must therefore be exerting a force on you to keep you from falling. That force is the weight that you feel.
As an example, a sky diver is in free fall towards the earth, and therefore feels weightlessness.
gravity

27. Example of Gravity – Weightlessness
If an object is dropped from rest, it will free-fall until it reaches the Earth.
However, if the object is given a velocity parallel to the ground, the compromise between Newton’s 1st law of motion and gravity will be a free-fall that always misses the Earth, which is an orbit. Because astronauts orbit the Earth in free-fall, they feel weightlessness.
velocity
gravity

28. Example of Gravity – a Planetary Orbit
Imagine a planet moving sideways with respect to the Sun. Newton’s first law says that it will continue to move sideways. But the law of gravity says that it will also be pulled towards the Sun. The result is a combination motion, in which the planet falls towards the Sun, but misses. This is an orbit.

29. Example of Gravity – a Planetary Orbit
Imagine a planet moving sideways with respect to the Sun. Newton’s first law says that it will continue to move sideways. But the law of gravity says that it will also be pulled towards the Sun. The result is a combination motion, in which the planet falls towards the Sun, but misses. This is an orbit.
If the Earth had been born at rest relative to the Sun, it would have fallen immediately into the Sun.

30. Example of Gravity – Binary Stars
According to Newton’s third law, just as the Sun exerts a force on the Earth, the Earth exerts a force on the Sun. However, since the Sun is so much more massive, it doesn’t move much. But if the Earth were more massive, the Sun would move.
Thus, Kepler’s 3rd law is not quite complete. The true law is
(M1 + M2) P2 = a3
where the orbital period (P) is in years, the semi-major axis (a) is in A.U.s, and the masses (M) are in solar units.

31. Example of Gravity – Tides
The effects of gravity do not depend on the composition of a body, just its mass and distance. The Moon exerts a force on the Earth, but since the Earth has a finite size, this force is different from one side of the Earth to the other. The side of the Earth near the Moon gets pulled most, the center of the Earth less, and the backside least of all. Since most of the Earth is solid, it doesn’t move much, but water reacts to this difference. So we have tides. d d

32. Summary Newton’s concepts: mass, velocity, acceleration, force
Newton’s Laws of Motion
inertia
Force = mass x acceleration
For every force, there is an equal and opposite force
Newton’s Law of Gravity
Gravitational force = GM1M2/r2
Explains trajectory of projectiles, planetary motion, tides, etc.
Corrected version of Kepler’s 3rd law: (M1+M2)P2=a3