Final Resting Place of a broken wood stick loaded with potential energy

Click For Summary

Discussion Overview

The discussion revolves around the dynamics of a broken wood stick, specifically a semi-rigid bow, that is loaded with potential energy and subsequently breaks while under tension. Participants explore the implications of the stick's breakage on its motion and landing positions relative to a vice, considering factors such as deflection, force application, and energy conservation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant queries the quantification of "semi-rigid," suggesting that the answer may depend on the degree of deflection and the properties of the rope used.
  • Another participant describes the scenario where, if the beam is perfectly rigid and the rope does not stretch, all forces would be relieved upon fracture, leading to a toppling motion.
  • A participant provides specific parameters, including a 6% elongation of the rope and a 10-foot bowing of the stick, and questions whether any part of the stick will land behind the vice.
  • One participant mentions that the deflection of the beam can indicate the force applied, suggesting that Hooke's Law and Newton's equations could be used to analyze the trajectory of the stick.
  • Another participant posits that due to momentum conservation, a portion of the stick must fall behind the vice, asking for theoretical confirmation of this idea.

Areas of Agreement / Disagreement

Participants express differing views on whether any part of the stick will land on the back side of the vice, with some suggesting it will all land on the side where it was pulled, while others argue that a portion must fall behind due to momentum conservation. The discussion remains unresolved regarding the exact landing positions of the stick.

Contextual Notes

Participants highlight various assumptions, such as the properties of the rope and the rigidity of the stick, which may affect the outcomes of the discussion. There is also mention of the need for specific calculations that have not been fully explored.

Werdna
Messages
3
Reaction score
0
If a 102 foot 2500 lbs. semi rigid straight wood stick (aka bow) is placed in a vice (a really big one with no give) and loaded with energy by pulling at the top, 50 feet above the vice at a 60 degree angle to the ground with a rope ("0" lbs.), where would the stick land if the stick instanteously broke in half two feet above the vice?

I am intersted to know if the pressure applied in the pulling direction will produce motion in the opposite and how much (e.g. how many feet of the stick will land on each side of the vice or will it all land on one side and by how far?)
 
Physics news on Phys.org
When you say "semi-rigid" can you quantify that at all? It seems the answer would depend on both the degree to which the beam was deflected and the "stretching" of the chain or cord or whatever you're using. If the beam is perfectly rigid and the chain doesn't stretch at all then all forces are relieved the instant the beam fractures and so it just topples over.
 
Your answer, in my words says all of the stick will be on one side. I follow that.

Answer to your questions

1. Rope has 6% elongation
2. The stick bows more at the top then bottom (like a tree) - Let's say it bows 10 feet from vertical center, measured at the 102 foot mark.

Now, will any of the stick land on the back side of the vice unlike the situation you described. If yes, what %?
 
I can't help you with the details but the deflection of the beam will tell you what force was applied to it. In turn, that force will give you the effective "spring constant" of the cord. Since you know how much the cord was stretched you can determine the force being applied to the "free" beam (Hooke's Law) while the cord remains stretched. You should be able to apply Newton's equations of motion to find the trajectory. I think it's likely the beam will land on the cord side since it's being pulled in that direction with no torque!
 
Since the process creates a spring and momentum is always conserved, a portion of the stick must fall behind the vice opposite the side it was being pulled on. Agree?

I don't need to know or do the equations, it has been a while, just theoretically will the stick land on both sides of the vice?
 

Similar threads

Jackhammer on Vehicle Suspension, Unsprung Mass, Tire patch load
  • · Replies 13 ·
Replies
13
Views
4K
High School Internal energy in the context of rest energy
  • · Replies 8 ·
Replies
8
Views
2K
Velocity of a particle kicked into four point charge square
  • · Replies 1 ·
Replies
1
Views
5K
Undergrad How is force applied? Is resistance or load necessary for force to exist?
  • · Replies 7 ·
Replies
7
Views
2K
Archived Potential Energy and Conservation Of Energy Atwood's Machine
  • · Replies 2 ·
Replies
2
Views
18K
Was the physics in old TV shows always accurate or just for drama?
  • · Replies 17 ·
Replies
17
Views
6K
How to compute flexure and failure loads of acrylic sheets
  • · Replies 4 ·
Replies
4
Views
16K
Writing: Input Wanted Generation Ship SFV Exodus: Revised Designs
  • · Replies 52 ·
2
Replies
52
Views
9K
Graduate Interesting paper, require feedback
  • · Replies 3 ·
Replies
3
Views
3K
Why is the U-2 nicknamed the Dragon Lady?
  • · Replies 4 ·
Replies
4
Views
9K