Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: heat and trapped water on moon

Learn more physics!

Most recent answer: 08/08/2013
Q:
My question is vacuum and heat related. Why is it that in a clip of Niel Armstrong and Buz Aldrin, when they demonstrate the feather and hammer falling at the same speed, why arent the feather or the wood handle of the hammer affected in any way? It was claimed that it was +360F in the sunlight. Wouldnt that have affected any molecules of water causing it to boil out of the wood and the fibers of the feathers? It must have been faked then right?
- Darryl (age 27)
Riverside, Ca, USA
A:

360°F isn't very hot. It's like a moderatley low oven temperature. Even rather moist foods don't dry out quickly at that temperature. You wouldn't notice any short term effect on any bits of water trapped in things like a hammer. As for boiling, the atmospheric pressure on the moon is so low that pure liquid water would boil even at much lower temperatures. That still has no short term effect on the water molecules trapped in materials.

There's a key thermodynamic point: water molecules don't boil individually. Boiling is a collective effect of large numbers of molecules. The boiling point of pure water is much lower than the boiling point of, say, a dense sugar solution. There is no boiling point for molecules trapped in some solid material, just some rates of molecules working to the surface and evaporating.

Mike W.


(published on 08/08/2013)

Follow-up on this answer.