How Does Gravity Affect a Flag Waved on the Moon's Surface?

Click For Summary

Discussion Overview

The discussion explores the behavior of a flag waved on the moon's surface, focusing on the effects of gravity and the absence of atmosphere. Participants consider how these conditions influence the flag's movement and appearance when waved.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant suggests that the flag would be stiff and point downwards due to gravity acting on it.
  • Another participant argues that the flag would not be stiff and could still be waved because it has mass and inertia, but it would not appear normal without air to fill it.
  • A participant references a famous image of Neil Armstrong with a flag on the moon, questioning why the flag appears to flutter despite the lack of atmosphere.
  • A later reply explains that the flag's movement is due to the astronaut rotating the pole, causing the flag to wave as it is attached at the top, rather than being moved by air.
  • Another participant questions the perception of the flag "fluttering" in a still image, suggesting that it may simply appear crumpled.

Areas of Agreement / Disagreement

Participants express differing views on the flag's behavior, with no consensus reached regarding its stiffness or appearance when waved on the moon.

Contextual Notes

Some assumptions about the flag's material properties and the effects of gravity in a vacuum are not fully explored, and the discussion does not resolve the nuances of how the flag's movement is perceived in images.

AnthreX
Messages
47
Reaction score
0
say that you have landed on the moon's surface
and you held the flag up and started to wave it around

moon has no atmosphere but has gravity right ?
than what would flag do when you wave it around ?

i am guessing that the flag would be stiff but it would be looking down towards the moon because the gravity is acting on it

any ideas/solutions ?
 
Physics news on Phys.org
No, it wouldn't be stiff. You could still wave it around, because it has mass and therefore inertia. It won't look quite normal, though, because there is no air to fill it like a sail.

- Warren
 
There's this famous picture of Neil Armstrong with an American flag on the moon staked to the ground. The flag looks like it is fluttering. I've always wondered: Why is that?
 
Originally posted by recon
There's this famous picture of Neil Armstrong with an American flag on the moon staked to the ground. The flag looks like it is fluttering. I've always wondered: Why is that?
"Of course a flag can wave in a vacuum. In the shot of the astronaut and the flag, the astronaut is rotating the pole on which the flag is mounted, trying to get it to stay up. The flag is mounted on one side on the pole, and along the top by another pole that sticks out to the side. In a vacuum or not, when you whip around the vertical pole, the flag will ``wave'', since it is attached at the top. The top will move first, then the cloth will follow along in a wave that moves down. This isn't air that is moving the flag, it's the cloth itself."

http://www.badastronomy.com/bad/tv/foxapollo.html#flag
 
Originally posted by recon
There's this famous picture of Neil Armstrong with an American flag on the moon staked to the ground. The flag looks like it is fluttering. I've always wondered: Why is that?
Besides, how can you see a flag "fluttering" in a still image? The flag is just crumpled.

- Warren
 

Similar threads

Replies
6
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
1
Views
2K
  • · Replies 30 ·
2
Replies
30
Views
5K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 32 ·
2
Replies
32
Views
4K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 21 ·
Replies
21
Views
6K
  • · Replies 9 ·
Replies
9
Views
3K