Hamster in Cage: Internal or External Forces?

Click For Summary

Discussion Overview

The discussion revolves around the mechanics of a hamster in a cage and whether the movement of the hamster can be attributed to internal or external forces. Participants explore the implications of friction and acceleration in this context, considering both theoretical and practical aspects of the scenario.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant suggests that the hamster could move towards an item by applying force against the cage, questioning whether this is feasible given the internal forces at play.
  • Another participant argues that the effectiveness of the hamster's movement depends on the nature of friction, noting that rapid changes in force can overcome static friction, unlike slower movements.
  • A third participant expresses that the explanation provided clarifies their understanding of the situation, indicating a level of complexity in the mechanics involved.
  • One participant introduces a broader perspective, mentioning that friction affects the system's isolation, implying that external factors must also be considered in the analysis.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the forces involved are purely internal or if external factors play a significant role. Multiple viewpoints are presented regarding the mechanics of the situation.

Contextual Notes

The discussion highlights the dependence on definitions of internal and external forces, as well as the role of friction and acceleration, which may not be fully resolved within the conversation.

cepheid
Staff Emeritus
Science Advisor
Gold Member
Messages
5,197
Reaction score
38
I remember seeing a commercial advertisement in which a hamster in a cage moved itself towards a desirable item (food or something) that its owner had on the counter by throwing itself against the side of its own cage. Would this really be possible? On the one hand it seems like there are only internal forces within a hamster/cage system. On the other hand, I can't think of why it wouldn't work. The hamster just needs to apply enough force to the side of the cage to overcome static friction between the countertop and the bottom of the cage.
 
Physics news on Phys.org
It works because the friction is slightly different for slow forces and fast changing forces.
It's the same principle as getting yourself spinning on an office chair.

In an ideal world the hamster running across the floor would move the cage backward as much as hitting the wallmoves it forward - in the real world the slow forward motion doesn't break the static friction, but the rapid accelearation of hamster+wall does.
 
Ohh...that's so simple once explained, but I couldn't seem to work it out.
 
To get mystical, the friction results in the system not being isolated. You end up having to consider the whole world(!)
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 35 ·
2
Replies
35
Views
5K
  • · Replies 15 ·
Replies
15
Views
4K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 4 ·
Replies
4
Views
7K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 17 ·
Replies
17
Views
6K