Post Gravitational Test

Okay we had a test today. How'd everyone do? Well the reason why I'm writing this is because I would like to know which part(s) of the unit did everyone have trouble with? Like what Mr K says, what were your muddiest parts? Clearest parts? Toughest? Easiest? You can post your thoughts in the comments section.

My muddiest part was combining the different formulas and equations. I can understand them individually but when they come together I take a bit longer working with them. My clearest part was the Kepler's 3rd law work, the formula with the ratio between the radii and period of the orbit.

So once again you can put your thoughts in the comment section and maybe we can help each other Past The Exam...

Review Before Test

Hi everyone. I'm going to be posting the review for tomorrow's test on gravitation and orbits.

REVIEW

Kepler's 3 Laws

For the orbital of planets the Sun is one focus point.

The areas created between 2 equal intervals of the planet's orbit are equal


Kepler's Formula


Newton's law of Universal Gravitation




Gravitational Potential Energy




Escape Velocity & g of a Planet or Sun & Orbital Velocity

Thanks Richard!

Newton's Thought Experiment
To stay in Earth's Orbit the satellite must have a velocity between 8km/s to 11.2km/s

Orbital Period


Microgravity
What is it?
-Environment with very little gravity

How can it be achieved?
-By gaining altitudes rapidly then suddenly decreasing altitude rapidly like during the NASA Microgravity Simulating Planes

Problems of Space Exploration
-Hazards
-Expense

That is all we had for a review. I might add more stuff if I find something but for now I'm getting some rest. I gotta study. Good luck tomorrow and the next scribe will be Francis.

Wednesday Dec 3, 2008

Sorry everyone i forgot to scribe yesterday. Today is Thursday, but am actually scribing for Wednesday. Hopefully no one gets confused.

This is the day where Richard & Eric presented their space exploration(mars). They were supposed to presented on Monday, however their video did not work. Their project was taped and cleverly done. The video contained humor, and rich information of the planet Mars.

Afterward, Mrs Kozoriz asked us to answer several questions from the review sheet. Here they are:

1. The radius of earth is about 6400 km. What would be the earth's gravitational attraction on 75-kg astronaut in an orbit 6400 k above the earth's surface?

6.67x10^-11(5.98x10^24)(75)/( 6400+64000)x2

Fg= 182 N

2. The Mass of Mars is about 6.6x10^23 kg. and the acceleration due to gravity is 3.7 m/s(2). What is the radius of Mars?


3. The Earth's radius 6400 km. A 25-kg mass is taken 20l km above the earth's surface.
a. What is the object's mass at this height?
- Mass does not change
- It's still 25-kg

b. What is the weight of the object at this height?

4. A sphere of mass 85 kg is 12 m from a second sphere of mass 65 kg.
a. What is the gravitational force of attraction between them?
b. What is the acceleration of the first sphere towards the second?


6. How many years would it take a planet located four times as far from the sun as the Earth to orbit the sun? The Earth's distance from the sun is 1.5x10^11 m.


Next Mrs Kozoriz went over the Gravitational fields worksheet. She only went over question # 7 & 8, but question 8 was not fully done. so i wont be answering it.

7. The planet Jupiter has a mass of 1.9x10^27 kg and a radius of 7.2x10^7 m. Calculate the acceleration due to gravity on Jupiter.

We've also watched a video about "Dark Matter" that took half the class. Well that was all for Wednesday.
We have a Test tomorrow so everyone study hard. This unit aint easy. Well then i gotta go and do ma math homework ... Pce

I've already told benjamen, so he's next to scribe. He might even be scribing now, who knows.

Monday dec 1st,2008

Hey everyone this is Jab....back on the class routine.
Today's class was fine and buzy.
First thing in today's class Mr. Joseph and Ms Shelly presented a presentation about the exploration of mars, soon as they finished Mr.Yonas and his partner (that's me) we took on the stage and presented about the biggest moon called Titan.
At last we watched a movie on weighlessness which we had to pick up seven points.

Mr. YONAS is next to describe.

Wednesday November 26 2008

Today in class the first thing we did was correct the questions that was assigned yesterday. On page 172 in the green book, Questions 9 to 12

Question 9 Answer : F = 8.0 x 10 ^-10 N
Question 10 Answer : F = 6.49 x 10 ^-8 N
Question 11a Answer : Fg = 491.3 N
Question 11b Answer : w = 490 n
Question 12 Answer : m = 9.01 x 10 ^-31 kg

The Next thing that we did was Watch some of the old Space Exploration Projects.

After that we then were taught to derive some formulas.




For number 1 you cancel out one of teh masses on each side.
For number 2 you cancel out one of the masses and radius on each side.
For number 3 you just cancel out one of the masses on each side.
She also gave us a forth one but she handed out a handout for this one.

The Next thing that we did was a review sheet for chapter 8.
And that was todays class the next scribe will be Kamil

November 25, 2008

To start things off we had gone over the questions on the Activity Sheet on Artificial Satellites and the Concept-Development practice page 14-1.

Here are the answers to the following:

Activity Sheet on Artificial Satellites

1) When the projectile is launched to a speed of 8km/sec
2) If it travels less than 8km/sec
3) around 8km/sec - 11.2km/sec
4)Yes, due to the atmosphere drag
5) about 850km - 35 800km
6) Yes
7) Yes, collisions with air particles slowly act to circularize the orbit and slows down the satellite. This causes it to drop to lower altitudes.

Concept-Development 14-1

1. d) Circle
e) Ellipse

2.d) Yes, the forces are the same strengh and are at equal distance
e)Yes, there is no acceleration
f) 90 degrees
g) No, "F" and "V" are perpendicular
h) No work is done
i) remains constant
j) remains constant

Right after we corrected the questions from the green book on page 172, and learned that the first 5 questions involves using this equation
(T1/T2)² = (R1/R2)³

Answers
1) 12 years
2) was to be handed in to Ms. K (answer: 19.2 Re)
3) 3.0724 Re
4) 22.63 years
5) 0.35Tm
6) 6.11 x 10^-9N
7) 4.17 x 10²³N
8) 5.84 x 10^-10N

Finally on the same page we are to work on next 5 (I think) questions.

Homework:
Questions 9 - 13 on page 172, Green book
Space projects are going to be due very soon!

Next scribe will be Richard

Physics November. 24, 2008

Today in class we watched a video about the "same same" teacher and the topic about the video was about the relationship of energy, gravity, and speed required to orbit and escape the earth, and the 's gravitational field, the vectors associated with the path of flight/orbit, and the shape of the orbits known as ellipses. It also explained why the paths of orbits were ellipses and how Kepler didn't see this visualization. Lastly, it went over the potential and kinetic energy relationships of the orbits.

Handouts on the "escape speed", "falling moon", "artificial satellites", and a practice sheet were given out.

Shelly blogs next..

I See Heavenly Bodies ;-)

Hello Hello,

This is Benofschool and for the record I didn't beg for this position as today's scribe. Well today we had a substitute and that person shall stay nameless because I do not have her permission to display his/her name online. Anyways we were assigned gravitational orbit and gravitational force questions from the Physics Green Textbooks. The questions are found on page 172 and questions #1-8 and including 8. For reference you can look at the past worksheet with planetary constants like the radii, period, and mass or you can look at page 159. I'd prefer the worksheet because it has all of the numbers required to answer the questions.

Sorry for the short scribe, but this is counted as a scribe. =P

Next scribe is Dana, but if he doesn't do it the next scribe will be Richard...

Okay I'm off to have a studying filled weekend =D

November 20, 2008

Walking into class, having a great day so far. Lawrence gave me a wonderful present. To scribe for today, what a nice guy huh? (Sarcasm). Anyways, let's get going.

The first thing we did today was the GRAVITATIONAL FIELDS WORKSHEET handed to us by the substitute teacher we had on November 19, 2008. (Mrs. Karras)

Next we were handed back our Transparency Worksheet (10)
I got the answers right so here they are.

1. 2M, 2M has the greatest force.
2. 2F.
3. Equal.
4. M1, M2, 2D = 1/4 F.
5. F=1.40 x 10 ^- 8 N.
6. 1/9 F.
7. 3F.
8. 3/4.
9. Remains the same.

Near towards the end of the class, we were handed a "Gravitational Potential Energy" booklet. If you don't have this booklet, get it because some very useful formulas are found at the back of this booklet.

Using this booklet, we were given a assignment (not due or anything) to finish in class. It's called "Gravitational Potential Energy Questions." Sorry I can't really give out the answers due to me leaving my Physics stuff in my locker or I might have lost it, I wouldn't know. Let's end this post by saying the next scribe is Benchman who begged me in class to blog for the weekend.

Wednesday, November 19, 2008

So by the blog, apparently Dana was supposed to be scribe, but upon my arrival to class, (Which was delayed due to my Phys Ed. Class, which took place at Sargent Pool) apparently Tony was chosen to be scribe, and since it was his birthday (which for some reason acts as a power of Veto), it was passed on to me. Honestly now.


Anyways, We basically went over the worksheets Ms. K assigned us the day prior. Mrs. Karras was also substituting.

Answers:

Study Guide 8

21) Cavendish used a rod with a ball on it, suspended from a thin wire. It also included a Large ball, a support, a mirror and a light source.









22) Force of attraction between the large and small balls caused the rod to rotate. It stopped rotating only when the force required to twist the wire equaled the gravitational forces between the balls.

23) F = G(M1*M2)/d^2 --> G = F*d^2/M1*m2 --> (6.67 *10^-11N)(1m)^2/(1kg)(1kg) = 6.67*10^-11 N*M^2/kg^2

Moving on, we went over the Chapter 11: Gravitational Interactions worksheet.

So since we know that if either mass in the equation for the law of universal gravitation is doubled, the force is doubled. Also we know that if the distance doubles, the force is one fourth of the original force.

1) If both masses are doubled, the force quadruples.

2) If the masses are not changed, but the distance of separation is reduced to 1/2 to the original distance, the force gets quadrupled.

3) If the masses are not changed, but the distance of separation is reduced to 1/4 the original distance, the force is sixteen times as much.

4) If both masses are doubled, and the distance of separation is doubled, the force remains the same.

5) If one of the masses is doubled, the other remains unchanged, and the distance of separation is tripled, the force is 2/9 of the original force.

6) The force remains the same (Force would be multiplied by 9, but because the distance is multiplied by 3, the force would be reduced to 1/9th of the original, keeping the force the same)

We then went over the Universal Law of Gravitation worksheet.

1) 7.41 * 10 ^-14 N

2) 81.82kg (In my case)
b)801.8 N (In my case)
c)180 lbs (In my case)

3)
a) Doubled
b) One quarter times
c) Four Times
d) Sixteen times

4) 1.62 * 10 ^ 6m

We were then handed a transparency sheet, which was later handed the same day. We were also given a Gravitational Fields worksheet, that would be due tomorrow I assume.

Next scribe is Tony.

Tuesday, November 18th, 2008

Today in class, we got some examples of what our big project should look like and then we went over a couple of sheets.

Here are the answers for the worksheets we corrected:

Chapter 8 Study Guide (Universal Gravitation):

Inversely
Square
F=G(M1 x M2)/R²
Force
R
Constant
Doubled
Halved
1/4

Chapter 8 Study Guide (Newton's Use of His Law of Universal Gravitation):

Second
Kepler's

Chapter 8 Study Guide (Weighing Earth):

Henry Cavendish
Attraction
Law of U.G.
6.67 x 10^-11 N x M²/Kg²

Chapter 8 Study Guide Section 8.1: Motions in the Heavens and on Earth:

1. True
2. True
3. False
4. True
5. False (Sun)
6. False (Area)
7. False (Ratios)
8. False (1st and 2nd)
9. Equal
10. 1
11. Rio -> need to calculate you need
Tio -> T + R of another of Jupiter's moons
12. C
13. A
14. D
15. B

We were assigned questions 16 - 23 on the "Chapter 8 Study Guide Section 8.1: Motions in the Heavens and on Earth" sheet and we also got 2 worksheets to do: "Universal Law of Gravitation" and "Chapter 11: Gravitational Interaction".

That's all folks, next scribe is Dana.

Kepler's Three Laws Videotape

No one was selected for scribe in physics, so I'm assuming today's scribe post is up for grabs.

I am zeph. zeph is scribe. Today's scribe post has been zephed!

Answers to "8.1 Motion in the Heavens and on Earth: Kepler's Laws of Planetary Motion" and "Kepler's Three Laws Videotape" are given below.

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8.1 MOTION IN THE HEAVENS AND ON EARTH

Kepler's Laws of Planetary Motion

Tycho Brahe studied the motion of the planets in order to be able to PREDICT astronomical events. He believed that EARTH was the centre of the universe. Johannes Kepler believed that THE SUN was the centre of the universe. He analyzed Brahe's data, and developed THREE laws of planetary motion. One law says that the paths of the planets are ELLIPSES with THE SUN located at one focus. Another law states that an imaginary line extending from the sun to a planet will sweep out equal AREAS in equal amounts of time. According to this law, planets move FASTEST when closest to the sun and move SLOWEST when farthest from the sun. Kepler's last law states that the ratio of the squares of the PERIODS of any two planets in orbit around the sun is equal to the ratio of the CUBES of their distances from THE SUN. This law can be states as an equation, (T_A/T_B)^2 = (R_A/R_B)^2. To use this law to calculate the period of a satellite, you must know the RADIUS of its orbit and the PERIOD and RADIUS of the orbit of another satellite.

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KEPLER'S THREE LAWS VIDEOTAPE

Answer the following questions based on the videotape entitled "Kepler's Three Laws".

1. What planetary model did Johannes Kepler believe in?
Copernican

2. What planet's orbit did Kepler analyze?
Mars

3. How far off from a circle was the oribt of Mars?
8 min arc or 1/4th of the apparent width of the moon

4. What type of curve can explain the orbit of Mars?
ellipse

5. In an ellipse, is the total distance from 1 pin to the string and then to the other pin a constant?
yes

6. The name given to a single point in an ellipse is the __________.
focus point

7. Focus is the Latin word for __________.
fireplace

8. How would you describe Kepler's childhood?
poverty and illness

9. What journey did Kepler undertake in 1600 and for what purpose?
went to see Tycho Brahe in Denmark to learn more astronomy

10. What was a main interest of Tycho Brahe?
astronomy

11. How did Kepler obtain the careful observations that Brahe made during his lifetime?
stole it

12. Was the Copernican model of the universe easy to justify scientifically?
no

13. What were some of the problems that faced Kepler in discovering the secrets of the sky?
planets are in motion in its orbit and rotates on axis

14. How many pages of calculations did Kepler have?
about 900 pages

15. What does "in opposition" mean according to the positions of Mars, Earth, and sun?
Mars is in the same position as the Earth and the sun

16. Can any circle viewed obliquely be termed an ellispe?
yes

17. In ancient history, which group of people studied conic sections?
Greeks

18. Is a parabola a popular shape in our world today?
yes

19. In your own words, describe he term eccentricity?
how flat an ellipse is

20. State Kepler's 3 laws.
a) 1st: Each planet moves in an ellipse with the sun as its focus.
b) 2nd: A line from the sun to each planet sweeps out equal areas in equal times.
c) 3rd: T^2 directly proportional to R^3

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HOUSEKEEPING
Homework:
* 8.1 Motion in the Heavens and on Earth Study Guide
* Exploration of Space Project due Thursday, November 27.
Next scribe is ERICT.

friday

Hey classmates.
in today's class we did a lab on chapter 8.
HAVE A GREAT WEEKEND.