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Originally posted by jra-2
Nobody know the real gravity of the Moon because nobody went there and measured it.
However gravity of the Moon has not to be so little if it can lift Oceans water.
It is instead a big truth that neither Northrop Grumman (Lunar Module builders) nor Lockheed Martin Corporation (Shuttle builders) have technology to build a rocket that can be used on the Moon to land there going backwards.
Actually LUNAR LANDER CHALLENGE is open to all big space companies.
The real American RETROROCKETS technology is this:
youtube.com...
Excuse me for repeating things but I'm waiting for someone that tell me:
"You are right".
[edit on 4-12-2007 by jra-2]
Originally posted by pepsi78
...Anything that weights above 1 kilo (in moon's gravity) on the moon would act like it is 1 kilo here on earth, it would fall and it would fall hard.
The moon gravity is lighter but one kilogram represented in moon's gravity will act just like one kilogram here on earth.
Let's take an object.
Points:
The object would be heavyer here on earth but it would weight 1 kilo on the moon.
Conclusion: the object would act like an object that has 1 kilogram in earth's gravity, 1 kilogram in moon's gravity acts the same as 1 kilogram in earth's gravity....
Originally posted by weedwhacker and someone can calculate the rate at wich objects are observed to fall,
Originally posted by pepsi78 the jumps and flips they preformed on the moon would be imposible in 1/6 gravity.
Originally posted by zorgon
Originally posted by weedwhacker and someone can calculate the rate at wich objects are observed to fall,
Well I have asked that in several threads and since we have a resident Phd here in physics maybe he could do that for us... The best film would be the hammer and feather drop...
It should be real easy to calculate, compare it to the same experiment done on Earth (in which both hit the ground at the same time as well) and then also calculate how long that would take in .64 g
No ofcourse that would have to presuppose that the videos are in real time and not 'speed adjusted' but we won't go there..
But so far no one has stepped forward to help...
It is interesting though that in the feather drop on the moon if you watch it frame by frame the feather does NOT fall perfectly straight... it shows wobble, almost as much as the experiment in a windless lab on Earth
Originally posted by zorgon
Originally posted by weedwhacker and someone can calculate the rate at wich objects are observed to fall,
Well I have asked that in several threads and since we have a resident Phd here in physics maybe he could do that for us... The best film would be the hammer and feather drop...
It should be real easy to calculate, compare it to the same experiment done on Earth (in which both hit the ground at the same time as well) and then also calculate how long that would take in .64 g
No ofcourse that would have to presuppose that the videos are in real time and not 'speed adjusted' but we won't go there..
But so far no one has stepped forward to help...
It is interesting though that in the feather drop on the moon if you watch it frame by frame the feather does NOT fall perfectly straight... it shows wobble, almost as much as the experiment in a windless lab on Earth
Originally posted by Soylent Green Is PeopleIf both balls dropped at the same time and from the same height, then they will both hit the ground at the same time.
Originally posted by Soylent Green Is People
Originally posted by pepsi78
...Anything that weights above 1 kilo (in moon's gravity) on the moon would act like it is 1 kilo here on earth, it would fall and it would fall hard.
The moon gravity is lighter but one kilogram represented in moon's gravity will act just like one kilogram here on earth.
Let's take an object.
Points:
The object would be heavyer here on earth but it would weight 1 kilo on the moon.
Conclusion: the object would act like an object that has 1 kilogram in earth's gravity, 1 kilogram in moon's gravity acts the same as 1 kilogram in earth's gravity....
No it doesn't. Objects fall more slowly on the Moon because of the Moon's lesser rate of "Acceleration due to gravity".
Acceleration due to gravity is what causes a parachutist to speed up as he/she freefalls. The longer the parachutist falls, the faster he/she will go, because of this acceleration rate (until air resistance keeps him from surpassing "terminal velocity", but we shall ignore air resistance for this debate).
"Acceleration due to gravity" on Earth is 9.8 meters per second per second (or m/s/s). "Acceleration due to gravity" on the Moon is only 1.6 m/s/s, so something dropped on the Moon would fall at a much slower rate on the Moon as it does on Earth, because gravity accelerates it faster as it falls on Earth than it would on the Moon.
So, going back to the parachutist example...on Earth, after 5 seconds he will be falling at a rate of approximately 49 meters per second (9.8 m/s x 5 seconds). On the Moon, that same parachutist will only be falling at a rate of approximately 8 m/s after 5 seconds of freefalling (1.6 m/s x 5 seconds). As you can see, an object on the Moon falls at a slower rate than on Earth.
By the way, It's irrelevant how much something weighs. A 1 kilo steel ball here on Earth will fall at the same rate as a 1000 kilo steel ball on Earth. If both balls dropped at the same time and from the same height, then they will both hit the ground at the same time.
Those two balls would also both fall at an equal rate on the Moon, and both will hit the surface of the Moon at the same time if they were dropped at the same time and from the same height -- although that rate WILL be less than on Earth, for the reasons described above.
[edit on 12/6/2007 by Soylent Green Is People]
Originally posted by zorgon
It should be real easy to calculate, compare it to the same experiment done on Earth (in which both hit the ground at the same time as well) and then also calculate how long that would take in .64 g
Originally posted by jra
Originally posted by jra-2
Try to balance a coke can on your finger. Difficult? Impossible?
Sure that's hard to do, but that has nothing to do with a VTOL rocket. It's a horrible comparison really. A coke can has its mass uniformly distributed throughout the entire can, where as the LM, for example, has most of it's mass on the bottom half and its center of mass is close to the point of thrust, so it's quite balanced, unlike a coke can on top of ones finger.
Originally posted by weedwhacker
...
For instance, was it you who said something about no one being able to build a spacecraft that could 'land' backwards? What does that mean?
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