PDA

View Full Version : Moon and no gravity



feathermoon
2007-May-19, 06:42 AM
I made a remark to my boss that "if we can make it to the moon" than we can do this....well, his response to me was "we didn't go to the moon", "if there is no gravity on the moon then how did the rover not float away?"....now this had me scratching my head.....why did the men not float away, is there absolutately no gravity at all on the moon, did we really land on the moon....all these questions. I have done some research today on line but can't find anything that can give me the "explanation" as to how the rover stays on the moon surface. I know the men used weights so why not the rover, right? :confused:

Fortis
2007-May-19, 06:57 AM
I made a remark to my boss that "if we can make it to the moon" than we can do this....well, his response to me was "we didn't go to the moon", "if there is no gravity on the moon then how did the rover not float away?"....now this had me scratching my head.....why did the men not float away, is there absolutately no gravity at all on the moon, did we really land on the moon....all these questions. I have done some research today on line but can't find anything that can give me the "explanation" as to how the rover stays on the moon surface. I know the men used weights so why not the rover, right? :confused:
The force of gravity at the surface of the Moon is roughly 1/6 that at the surface of the Earth. That is more than enough to prevent to rover floating away.

Occam
2007-May-19, 02:01 PM
I made a remark to my boss that "if we can make it to the moon" than we can do this....well, his response to me was "we didn't go to the moon", "if there is no gravity on the moon then how did the rover not float away?"....now this had me scratching my head.....why did the men not float away, is there absolutately no gravity at all on the moon, did we really land on the moon....all these questions. I have done some research today on line but can't find anything that can give me the "explanation" as to how the rover stays on the moon surface.
Did your "research" extend as far as typing "gravity of the moon" into Google, which gives 1,360,000 articles?

I know the men used weights so why not the rover, right? :confused:
Wrong. How do you 'know' something this incorrect? How would the use of weights help in zero gravity?

It's stuff like this that makes me despair.

Hamlet
2007-May-19, 05:13 PM
I made a remark to my boss that "if we can make it to the moon" than we can do this....well, his response to me was "we didn't go to the moon", "if there is no gravity on the moon then how did the rover not float away?"....now this had me scratching my head.....why did the men not float away, is there absolutately no gravity at all on the moon, did we really land on the moon....all these questions.

First of all, welcome to the BAUT! Second, yes we did land on the Moon. Third, everything with mass has gravity. This includes the Moon and any other celestial body you care to name. You have mass too, so you are exerting a gravitational force on your surroundings. The gravitational acceleration you experience is proportional to the mass of the body and inversely proportional to the square of the distance between you and the center of the body.

The formula that expresses this relationship is: g = GM/r2

Where:

g = gravitational acceleration
G = gravitational constant (6.673 x 10-11 m3/kg s2)
M = mass of body
r = radius from the center of the body to measurement point.

For example, gravity at the Earth's surface can be computed using the following:

Mass of the Earth: 5.97 x 1024 kg
Radius of the Earth: 6.378 x 106 meters

Plug these values into the formula gives: gearth = 9.79 m/s2

Now do the same thing for the Moon:

Mass of Moon: 7.35 x 1022 kg
Radius of the Moon: 1.738 x 106 meters

Plug these values into the formula gives: gmoon = 1.62 m/s2

You can see that as Fortis mentioned, the gravity of the Moon is about 1/6 of that of Earth.



I have done some research today on line but can't find anything that can give me the "explanation" as to how the rover stays on the moon surface. I know the men used weights so why not the rover, right? :confused:

The reason you couldn't find anything is that your premise is wrong. There is gravity on the Moon, so the answer to how the men and rovers stayed on the Moon is simply gravity.

Why do you think the men used weights? How do you think this would have helped if there were no gravity?

feathermoon
2007-May-19, 11:11 PM
Thank you all for your explanation. Now I can actually give my boss some facts. I was using the premise of "no gravity" due to my boss' statement...and as far as using weights - well, I just assumed without really understanding gravity and mass. I need to do some more studying and not sound so unknowledgeable....sorry about that. But you all answered my question and now I understand. Thanks again!

feathermoon
2007-May-19, 11:21 PM
Boy do I ever need to go take some science classes again...it's only been 40 years.... But, I know I came to the right place and got the answer I needed.... I am very interested in our universe, solar system, planets etc...and want to learn more...so I'll stick around if you guys don't kick me out with some of my stupid questions... so thanks again!

Hamlet
2007-May-20, 12:20 AM
Thank you all for your explanation. Now I can actually give my boss some facts. I was using the premise of "no gravity" due to my boss' statement...and as far as using weights - well, I just assumed without really understanding gravity and mass. I need to do some more studying and not sound so unknowledgeable....sorry about that. But you all answered my question and now I understand. Thanks again!

No need to apologize. No one is born knowing this stuff. We've all had to learn along the way. It's to your credit that you took the initiative to find out the facts.

Stick around and ask your questions. There are lots of knowledgeable people who post here.

Ilya
2007-May-20, 01:52 AM
Are you sure you want to tell your boss that he is ignorant, gullible, or both?

Gsquare
2007-May-21, 02:53 AM
Thank you all for your explanation. Now I can actually give my boss some facts. I was using the premise of "no gravity" ......!

If you really wanna blow him away, show him this video of an astronaut on the moon's surface dropping a feather and a hammer from the same height and both hit the ground at the SAME time. :eek:

http://www.youtube.com/watch?v=dHzVsLAhUCA

Of course, the lunar conspiracy theorists will have fun with this one. :D

OneHotJupiter
2007-May-21, 02:45 PM
I do love that clip , there is a better quality version on Youtube somewhere that is not so grainy , I still get a kick out of the "How 'bout that" quote , Lordy I do love science!

redshifter
2007-Jun-05, 12:29 AM
Are you sure you want to tell your boss that he is ignorant, gullible, or both?

Just wait till after your review...:lol:

Identity 4
2007-Jun-05, 03:42 AM
If you really wanna blow him away, show him this video of an astronaut on the moon's surface dropping a feather and a hammer from the same height and both hit the ground at the SAME time. :eek:

http://www.youtube.com/watch?v=dHzVsLAhUCA

Of course, the lunar conspiracy theorists will have fun with this one. :D

Hm...looks like they already did....or at least SOME kind of nut theorists.. (for context please refer to youtube comments regarding said video). Just did some skimmg, mostly angry flaming and name calling...lol

feathermoons's question at the start of thids thread brings up a neat thought. Let us pretend that the moon DIDNT have any gravity (odd, i know, but hypothetical). I figure NASA is a bunch of smart guys, they would have known this. Ok. So how does one stay on the moon in this condition? Forces! even a tiny trickle of a gas jet towards they sky would probably be sufficiant to hold the spacecraft to the ground. As for the astronauts, just hope they dont jump to hard..lol! :shifty: Hooray for the real moon having gravity, eh? :)

-=Identity 4=-

joshuatree
2007-Jul-22, 03:06 AM
If you really wanna blow him away, show him this video of an astronaut on the moon's surface dropping a feather and a hammer from the same height and both hit the ground at the SAME time. :eek:

http://www.youtube.com/watch?v=dHzVsLAhUCA

Of course, the lunar conspiracy theorists will have fun with this one. :D

Of course the "conspiracy theorists" that you refer to are the ones at nasa right?

There is absolutely no proof that can't be disproven that we landed on the moon. Just as the nasa conspiracy theorists would tell you that the moon hoax debunkers theories can all be disproved.

And whats the big deal about the feather? Filmed at double speed to provide a slow mo? Or are you going to tell me the film cameras taken to the moon couldn't change film speeds. Of course that explains its authenticity. No way it could have been shot on the earth and then shown on the big projector screen at nasa for all the television crews.

Jeff Root
2007-Jul-22, 06:09 AM
There is absolutely no proof that can't be disproven that we landed on
the moon. Just as the nasa conspiracy theorists would tell you that the
moon hoax debunkers theories can all be disproved.

And whats the big deal about the feather? Filmed at double speed to
provide a slow mo? Or are you going to tell me the film cameras taken
to the moon couldn't change film speeds. Of course that explains its
authenticity. No way it could have been shot on the earth and then
shown on the big projector screen at nasa for all the television crews.
On the chance that you actually are serious about this, not just
having fun being goofy, I'll ask you this question: What do you
think was the purpose of the hammer and feather demonstration?
From what you say above, it looks as though you don't know.

-- Jeff. in Minneapolis

DaveC426913
2007-Jul-22, 03:28 PM
The hammer/feather experiment isn't about how fast they fall, it's about the fact that they both fall at the same speed.

It is less a demonstration that they are in low gravity and more a demonstration that they are in vacuum.

Paul Beardsley
2007-Jul-22, 07:07 PM
On the chance that you actually are serious about this, not just
having fun being goofy, I'll ask you this question: What do you
think was the purpose of the hammer and feather demonstration?
From what you say above, it looks as though you don't know.

-- Jeff. in Minneapolis

He's serious, Jeff. Tragically serious.

Check out the What Happened On The Moon? thread in Conspiracy Theories. Read that, and you'll know not to expect any sensible answers.