About planetary gravity

[JarodRussell]

RB_Kandy wrote:

---

I recently found out that gravity on any given planet is caused by the mass of the planet.

I had always assumed that gravity on a planet was caused by the speed of rotation, orbit, proximity to the sun, and size of the sun.

I began exploring why gravity didn't get stronger during its ellipse when it was closest to the sun, and less when it was far. It was googling that which lead me to realize the size of the planet was the cause of gravity.

But I am wondering, does speed of orbit and rotation play any part of planetary gravity?

Just why did you think that the SUN was causing us getting pulled towards the Earth? Or that the rotation of Earth would pull us towards Earth? Have you ever been on a carousel, and where you pulled inward or outward by the rotation?

Glad you recently found out that gravity is caused by mass.

Now, orbital speed, the planet's rotational speed, the gravity of the sun, the gravity of the Moon, they all affect the gravity of the Earth.

If Earth wouldn't spin, gravitational pull would naturally be a bit stronger. The Moon's gravity pulls on Earth and anything: it causes tides (because the whole body of water is pulled towards the Moon, and the Earth rotates through that water "hill"), earthquakes, and the gravitational friction constantly reduces the Earth's rotation speed. The gravity of the sun affects us more when Earth is closer to the sun, and less when it's farer away from the sun, naturally. But it's a pretty minor difference. And yeah, even the sun causes tides, just like the Moon.

[Trekker4747]

And anyone who's ever ridden on a merry-go-round or other spinny-type ride knows that the rotation tries to throw you OFF of it not pull you more into it. If Earth's spin were to have any real impact on us it'd be more likely to throw us into space than it would to pulls us into it. Thankfully, gravity is stronger than centripetal force.

[Crazy Eddie]

gturner wrote:

---

Perhaps we should keep things simple. Gravity is the force that attracts liquids to your keyboard.

Which is why you should turn your chair sideways while watching internet porn.

[RB_Kandy]

First, I would like to start off by explaining that my school was a very stupid school that made no effort to educate. In middle school and early high school my subjects were History, Social Studies (history and political correctness), and English (part history part social studies), PE, Art & Music, Math, Science, and Lunch. Damn I did good in Lunch, it was my best subject.
Science class in middle school was pretty cool, and super easy. Thus I am guessing we weren't really learning much. I remember there being lots of props that did odd things, and then we would be explained why it worked like that. Example, a device with a metal dome that send electricity through your body, made your hair stand on edge, and you had to stand on a crate.


In high school science class consisted of, two years in a row, this science teacher that just lectured people on the utmost irrelevant things. If you've seen Mr. Garrison on South Park, and the way he teaches class, you have to understand, that's almost exactly how this teacher was.


I failed math because when I changed schools, I some how went from 6th to 7th grade, because I got held back in 2nd grade. When I got into 8th grade math, it was super hard, and I couldn't understand it. My teacher just kept giving me an F and lecturing me on how smart I am, and how I CAN do this if I just apply myself. I honest to god couldn't do it because I skipped certain mathematical knowledge. It's like learning HTML, skipping the year they teach you Java, and going right to PHP and MySQL, and it is assumed you know Java. You'd never pass, because every time they'd ask you to write a Java script to defer to the MySQL data base, you'd just sit there like WTF!?


Now I do remember my Social Studies teacher teaching us all about Science... in social studies class.
It started out by learning about all the black and Hispanic scientists that have contributed to science. And some how moved in to her teaching science.
She freakin told me the earth's rotation is what made gravity and pulled us inward.


I recall saying "wouldn't the spinning of the earth push us outward? Like, if you dip a basketball in water, and then spin it on your finger, the water goes outward and splashes you, because spinning pushes objects away from the surface" she says "no, because we're also orbiting the sun."


I just nodded my head, not understanding it, and assuming I was too stupid to understand it.


And the thing is, a week later I am talking about it to a friend (who has the same class) and he's explaining how the teacher is totally right.


I recall from other history, social studies, and English teachers, that Edison invented the light bulb. George Washington Carver invented peanut butter. Some black guy in world war one invented the radio. Benjamin Franklin accidentally discovered electricity when flying a kite in a storm. Christopher Columbus discovered America. Leonardo Da Vinci invented the first air plane.


I was taught a lot of stuff that wasn't true.


But in science classes, throughout elementary school, it was all about home made volcanoes, and interesting "tricks" you could do at home.


In middle school (because 6th and 7th grade over lapped for me) I only had two science teachers, and only my 8th grade science teacher, Mr. Little, actually attempted to teach us about science.
I look back at school, and besides the students, and the social environment, all I can remember about the lessons were Rosa Parks, Martin Luther King, Malcolm X, Susan B Anthony, Second Wave Feminism, and reading The Grapes Of Wrath, Of Mice And Men, Greasers, and a lot of books that remind me of The Fox And The Hound. And learning about historical people who we were told invented or discovered things they didn't.
To this day, I still remember my 9th and 10th grade science teacher the day he had to take his dog to the vet, and that got us learning about the miracles of Vitamin B. And for the rest of the month we learned about Vitamins... In Earth Science class! I remember he made a speech about the laws of the road, and how at 60 MPH some special inertia takes place. I remember him briefly touching on the theory of relativity. We learned about global warming, and recycling, I remember that because he looked at me and my best friend and said "You two could at least recycle your beer bottles". And when he caught his son coming home drunk, and made him drink more until he puked his guts out, to teach him a lesson. All of which is interesting, because 2 years after I dropped out of high school, and worked at my family's liquor store (18 to sell it as long as there is no open container in the establishment) he used to come in there every day, by a huge fifth of brandy, and he never recognized me as a former student. Apparently he lost his job a year after I quit school, and he died two years after that. He literally drank himself to death.
Oh yeah, in one of the years he was teaching us about whales for a couple of months. And he did mention Star Trek The Voyage Home.
You know, to this day, I don't know what the hell Earth Science is.
To this day I get a lump in my throat when I hear "Earth Science" because all I can think about is whales, alcoholism, global warming, vitamin B, and the fact that boys can hold it in longer than girls, so boys can't leave the class room, and neither can the girls because they only go there to do their makeup. The teacher was off the charts crazy.

[gturner]

Wow. That sounds horrible.

I had an idiot science teacher in 7th grade who insisted that atomic bombs are more powerful than hydrogen bombs because atomic bombs are fission, which throws things outwards, and hydrogen bombs are fusion, which is an implosion that sucks things inwards. I sat there thinking, "That's so stupid it's not even wrong!"

Gravity is an attraction between two masses, with the formula Force = G * M1 * M2 / R^2, where M1 and M2 are the masses of the two objects, G is a constant, and R is the radius between their centers.

[Maurice]

I'm not going to address that litany of "they done me wrongs" and thinly veiled jabs at the left above, but it's pretty well established that there's a lot of history taught that's baldly incorrect.

American history has often mythologized in public school textbooks due to the needs of the textbook industry to placate local school boards. This is why we get whitewashed versions of Helen Keller, Reconstruction, etc., and persistent myths like Betsy Ross.

[JarodRussell]

Oh come on, surely you were taught about basic Newtonian physics, regardless of how much your teacher rambled.

[Christopher]

Yeah, sometimes teachers are a crapshoot. I went to a high school that's considered one of the finest public schools in the United States, yet I still got a biology teacher who was a creationist and a health teacher who was a mortician. I did get some really great teachers, though, like a physics teacher who was an actual professor.

[sojourner]

a mortician for a Health teacher? that could have been interesting.

[Christopher]

^Just try to imagine learning sex education from a sardonic, middle-aged mortician who sounds like Fat Albert's Mushmouth without the speech impediment.

[Tiberius]

Christopher wrote:

---

^Just try to imagine learning sex education from a sardonic, middle-aged mortician who sounds like Fat Albert's Mushmouth without the speech impediment.

Better than learning about sex from a middle aged person who's sworn to be celibate and gets his information from a book written by people two thousand years ago...

But let's not go down that road...

[Tiberius]

RB_Kandy wrote:

---

I remember he made a speech about the laws of the road, and how at 60 MPH some special inertia takes place.

Actually, it's 88mph.

[RB_Kandy]

Maurice wrote:

---

I'm not going to address that litany of "they done me wrongs" and thinly veiled jabs at the left above, but it's pretty well established that there a lot of history taught that's baldly incorrect.

American history has often mythologised in public school textbooks due to the needs of the textbook industry to placate local school boards. This is why we get whitewashed versions of Helen Keller, Reconstruction, etc., and persistent myths like Betsy Ross.

Well they did do me wrong
Of course they did everyone wrong. My old high school had some pretty incredible drop out rates.

Of course it's 100% my own fault that I never to this day got my GED.

Come to think of it, I failed metal shop through lack of trying, so I guess by 9th grade I was failing my teachers as much as they were failing me.

Hmm, I was wondering why so much of school taught history is incorrect.
I mean, the first thing that springs to my mind is "damn leftist politics" (which there was a lot of, jab jab) but the reality of it is a lot of the stuff I learned that was false, had no political motivation behind it.

You say it's because the textbook industry is trying to make money? or are you saying they are trying to fill some sort of quota?

And what Betsy Ross myths are you talking about?

JarodRussell wrote:

---

Oh come on, surely you were taught about basic Newtonian physics, regardless of how much your teacher rambled.

Actually my 8th grade science teacher, Mr. Little, did teach us about Newtonian physics. He had this lovely demonstration, he said "You know how women love to wear lipstick to make their lips all waxy? Karen, I want you to stand up and wet your lips. Just give 'em a quick lick like this."
After she licked her lips he said "there you go folks, that's our physics lesson. Wet waxy lips. Or WW LIPS. Which stands for Wheels, Wedges, Levers, Inclines, Pulleys, Springs"

He had made the big deal of making Karen lick her lips for the spectacle so that we'd remember it, considering we were going to spend the second half of the year learning about those exact things, and about Newton's laws of motion, and building devices using those principals, and explain the motion, the cause and effect, with the laws of newtons physics.

And because I had the biggest crush on Karen, I'll never forget her wetting her waxy lips.

I only remember the name of two of my teachers. Mr. Little, because he was my favorite, and actually the teacher who got me to care about science. And Mrs. Greene, because good god that woman had legs LOL

Christopher wrote:

---

Yeah, sometimes teachers are a crapshoot. I went to a high school that's considered one of the finest public schools in the United States, yet I still got a biology teacher who was a creationist and a health teacher who was a mortician. I did get some really great teachers, though, like a physics teacher who was an actual professor.

A creationist biology teacher and a health teacher that was a mortician. Oh I could just see his speeches "and here are the 5 things you can do to make sure you never have to come see me at my other profession, eat right, exorcise, don't smoke..."

I just remembered another teacher I liked, how he inspired all of us, and how he was wrongfully fired. I'll put this in a spoiler tag so everyone can skip it.

Actually I just remembered another teacher. Mr Thompson, either 8th or 9th grade PE teacher. He was really good. He was all about "trying" and team spirit. And if you didn't do well in his class, near the end of the semester, he'd pull you to the side, and really giving you a polite talking to about how he grades on effort, individual progress, group participation, and sportsmen conduct. How you can come in last in the race, and still get an "A" if you finish the race faster than last time, and had a good positive attitude.

I remember one day, I was chosen as team captain for basketball practice, and my opponent went first. He chose Darnell who's nick name was "wings" because he could fly through the air and slam dunk. I made my choice, and then Charles walked in, saying he is sorry for being late. My opponent got to choose him. The best damn basket ball player in the entire neighborhood. And my opponent (the other captain) was probably the third best basket ball player. So their team had the three best players (by a land slide). Because these three men were like professional NBA stars, versus a bunch of pudgy little white boys and girls, we knew there was no way my team had a chance no matter who else I picked. So lo and behold my opponent started choosing the absolute worst people to fill out the rest of his team. He chose the fat people, skinny little white girls afraid to break their nails, and all the stereotypical nerds. The people who had a reputation in our class as being the least athletic, and the most shy and socially awkward.

We played, and they're team still won LOL. But afterward, I heard Mr. Thompson talking to the team captain (can't remember his name) and he commended him for choosing the team the way he did.
You see, the team captain wanted to make it fair, he knew he had the three best ball players in the school, so he chose all the weakest people, passed the ball to them. Made them, forced them, to be a part of the team, and then made them all feel like winners by winning. All the while giving my team a fighting chance.

That was the kind of spirit Mr. Thompson could inspire in us.
A few years later the school fired him for being homosexual.
Talk about messed up. They fired one of the few teachers who ever made a positive impact on anyone, just for being gay. Not that he was gay with his students or any scandal like that.
And what shocked me was, this was a school that beet you over the head with liberal tolerance and equality, they just didn't want to practice what they preached.

Further proof that yes, there are some good teachers, but man, something was just wrong with my school district.

I am wondering what you guys think of this solar system theory that earth is not revolving around a stationary sun, but is instead traveling in a spiral. http://www.youtube.com/watch?v=o6jBK...eature=related

[sojourner]

Piece of advice. Youtube is NOT the place to learn new "theories".

[Tiberius]

Some of the stuff on youtube is good. But that was crap.