Anatomy in a reduced gravity enviroment

[John_S4x4]

A question or two. When the Apollo astronauts landed on the moon, did their privite bits shrink, as their was less gravity acting on them ?
If they went to the moon where the gravity is 1/6th of what it is here, surely their love troucheon wouldn't be so long, as gravity wouldn't be 'pulling it down' so much ?
No women went to the moon, so we would have to guess what happens to them. I suspect that womens chests wouldn't sag so much and hence would benefit from a 'free boob job' ?
So I also presume that Lunar jogging seen at normal speed would be pretty much like the infamous slow-motion beach jog scene. Everything will happen slower in low-G, the ups, the downs, the bounces... all slowed down to 1/4 time ?

[groucho]

Don't know about any of that, but imagine what you could bench press.

[JonRB]

groucho said:

Don't know about any of that, but imagine what you could bench press.

Don't be so sure. The weight of the, er, "weights" would be reduced, but they would have the same mass and hence momentum, which could easily crush you just the same as on Earth.

[groucho]

Now we're getting into physics . So a bar that weighs 150 kilos on earth, would in theory weigh 25 kilos on the moon if it has one sixth of gravity?
I don't know, I'm just asking.

[Eric Mc]

They were TOTALLY weightless all the way to the moon and back. As indeed, are any of the astronauts who travel on the Space Shuttle/Soyuz or stay in the International Space Station.

Low or zero gravity is a serious problem for those who have to stay in space or on a low gravity planet for any length of time. The Apollo astronauts were not unduly impaired on return to earth mainly beacuse none of the Apollo missions lasted more than 14 days. Astronauts staying on the Skylab space station in 1973/74 were much more seriously affected by the low/no gravity environment.
The Russians have had their problems too with cosmonauts returning from their space stations (Salut/Mir etc). However, because of the vast experience built up by the Soviets/Russians they came up with various exercise regimes and programmes to try to minimise the debilitating affects of exposure to long term weightlessness. Although not 100% effective, they do go a long way to help and these practices are now undertaken by astronauts who are on long stay missions to the International Space Station.

Regarding mass and weight, a 1 tonne mass will squash you just as effectively on the moon as it would on earth. The astronauts on the moon did experience difficulties an moving around under 1/6 G. Some of their problems were down to the sheer bulk of the space suits and backpacks and quite a few of the astronauts actually fell over. Changing direction needed a bit of forethought.

>> Edited by Eric Mc on Friday 17th June 13:30

[JonRB]

A bar that masses 150 kg on Earth would still mass 150 kg on the moon. However, the force due to gravity (ie. the weight) would indeed be 25kg, since F = m*g (where m = mass and g = gravity).

Edit: But as Eric points out, momentum is a product of mass, not weight, so when changing direction you have the same momentum as on Earth.



>> Edited by JonRB on Friday 17th June 13:35

[GasBlaster]

JonRB said:

groucho said: Don't know about any of that, but imagine what you could bench press. Don't be so sure. The weight of the, er, "weights" would be reduced, but they would have the same mass and hence momentum, which could easily crush you just the same as on Earth.

So how much can you bench press on the moon then?

[zaktoo]

Eric Mc said:

Some of their problems were down to the sheer bulk of the space suits and backpacks and quite a few of the astronauts actually fell over. >> Edited by Eric Mc on Friday 17th June 13:30

They probably tripped over the power cables to the cameras that were filming them in the studio...

:runsandducks:

[JonRB]

GasBlaster said:

So how much can you bench press on the moon then?

Well, assuming that on Earth you were sufficiently strong to press 150kg, then since F = m*g (as we've already established), and given that you are able to exert the same force F that raised 150kg on Earth, then for a smaller value of g, m must be higher. So, yes, you could lift 6x more on the Moon as the Earth.

The trouble is, as it starts to fall back down, it has a momentum of mass * velocity. So if you let the bar fall too much (ie. allow the velocity to increase) then you must supply the same force as you would on Earth, which if you are lifting 6x more than you would on Earth is going to be more than you can supply and you would be crushed.

[Eric Mc]

Zaktoo - John Young DID fall over a power cable on Apollo 16. He ripped the cable out of the very important "Heat Flow Experiment" which was intended to find out if the moon had a molten core or not.
The experiment was ruined and Young was very upset by what he had done.

[catretriever]

JonRB said:

[quote=GasBlaster] The trouble is, as it starts to fall back down, it has a momentum of mass * velocity. So if you let the bar fall too much (ie. allow the velocity to increase) then you must supply the same force as you would on Earth, which if you are lifting 6x more than you would on Earth is going to be more than you can supply and you would be crushed.

no I don't think that's right. It's Newtons 2nd law that applies

F=ma

the force excerted by the weights will equal its mass * it's acceleration (which in this case is the moons gravity 9.8/6 or something)

or I might be wrong

[eharding]

John_S4x4 said:

If they went to the moon where the gravity is 1/6th of what it is here, surely their love troucheon wouldn't be so long, as gravity wouldn't be 'pulling it down' so much ?

Well, I can personally confide that pulling +7G
with an ill-positioned crotch-strap buckle does
one's nads no favours whatsoever.



>> Edited by eharding on Friday 17th June 15:56

[groucho]

GasBlaster said:

JonRB said: groucho said: Don't know about any of that, but imagine what you could bench press. Don't be so sure. The weight of the, er, "weights" would be reduced, but they would have the same mass and hence momentum, which could easily crush you just the same as on Earth. So how much can you bench press on the moon then?

Haven't done it for a couple of years, but then 900 kgs

[JonRB]

catretriever said:

no I don't think that's right. It's Newtons 2nd law that applies F=ma the force excerted by the weights will equal its mass * it's acceleration (which in this case is the moons gravity 9.8/6 or something)

That is the force due to gravity.
F=ma is the generalised form of F=m*g which I've already quoted.

However, the force required to stop, or change the direction, of a moving body is dictated by its momentum.