1. Charting the Sky - 4 Mr. Jean
Option D
Charting the Sky - 4
Mr. Jean

3. Newton’s Cannon:
In the late 1600’s Sir Issac Newton predicted that space travel was actually possible.
Here’s his idea:
If you are able to build a cannon with enough power, it could shoot a projectile with enough speed to travel far enough horizontally that any free fall of the cannon ball would be offset by the curivature of the earth.

5. More on Newton:
Amazingly Newton’s understanding of physics and the equations of motion he created give us the ground work for space travel and so much more.
This book also includes most of the fundations to upper level mathematics. (Calculus in particular)

6. What is important for this unit:
You should be able to calculate the force of gravity.
To calculate the gravitational force on a planet
Calculate the orbit of a planet
Calculate the orbital speed of a planet

12. Gravity and Orbits & Gravity Lab Activity
Learning Goals- Students will be able to
Draw motion of planets, moons and satellites.
Draw diagrams to show how gravity is the force that controls the motion of our solar system.
Identify the variables that affect the strength of the gravity
Predict how motion would change if gravity was stronger or weaker.
phet.colorado.edu

13. If our sun were twice as massive, how might the earth movement change?
B. In the cartoon mode, the earth crashes into the sun, but in reality, the path is just reduced in size.
The earth would definitely crash into the sun
B. The path would be smaller
C. The path would not change 13

14. Which vector representation would show the moon between the earth and the sun? (black arrow Total Gravity Force moon) B.
Most students chose A because the vector appears to be the smallest, which would make sense if you think of vector addition of the gravity of the earth and gravity and sun although the moon vector is not to scale compared to the earth sun vector. C. 14

15. Use the simulation to show the path of the moon and the resulting vectors.
Remember that the placement of vectors in space is arbitrary. The point (0,0) can be anywhere.
Review that the placement of vectors in space is arbitrary. 15

17. Newton’s Law of Universal Gravitation:
Fg = force of gravity in newtons (N)
m1 = first mass in kilograms (Kg)
m2 = second mass in kilograms (Kg)
r = distance between centers of mass in meters
G = Universal Gravity Constant (***next slide for units***)

18. Practice Questions:
At this point we want to make sure that Newton’s Law of Gravity and it’s formula is well understood and familiar.
Try the following questions.
Solutions are on the slides to follow.

22. Challenge Question #7:

25. Practice Question:
A planet which has the radius of 10,000km has a mass of 2.9 x 1027kg.
1) What is the gravitational field intensity on the planet?
2) How far is the planet away from the sun if the force of gravity between the planets is 9.5 x 1024N?
3) How fast is the planet moving around the sun if it is (part 2) ____ distance away from the sun?

26. Practice Question:
A planet which has the radius of 10,000km has a mass of 2.9 x 1027kg.
1) What is the gravitational field intensity on the planet?

27. Practice Question:

28. Practice Question:
A planet which has the radius of 10,000km has a mass of 2.9 x 1027kg.
2) How far is the planet away from the sun if the force of gravity between the planets is 9.5 x 1024N?

29. Practice Question:

30. Practice Question:
A planet which has the radius of 10,000km has a mass of 2.9 x 1027kg.
3) How fast is the planet moving around the sun if it is (part 2) ____ distance away from the sun?

31. Practice Question: