Is 5 N/m² a Reasonable Young's Modulus for Wood?

Click For Summary

Homework Help Overview

The discussion revolves around determining a reasonable value for Young's modulus of wood based on experimental results from a practical involving a wooden metre rule. The original poster calculated a value of 5 N/m² and seeks to compare it with accepted values.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the implications of the calculated value, question the accuracy of units, and discuss the relationship between beam thickness and Young's modulus. There are attempts to clarify the definition of modulus and its dependence on material properties.

Discussion Status

The discussion has evolved with participants recognizing errors in calculations and the need to re-evaluate results. Some guidance has been offered regarding the common experimental methods for determining Young's modulus, and there is acknowledgment of the variability in measurements.

Contextual Notes

Participants note the potential for significant errors in calculations due to scale and unit misinterpretation. The conversation highlights the importance of accuracy and the need for correct order of magnitude in experimental results.

lionely
Messages
574
Reaction score
2
I did a practical worked the gradient and calculated E, of a wooden metre rule.

What I want is a value to compare my value with, I got 5 N/m2

So 5N will bend the ruler 1m? Seems likely right?
 
Physics news on Phys.org
On that page isn't that Mega Pascals?? I got 5Pa
 
and maybe on that page those are MUCH higher maybe cause they calculated it using woods of greater thickness,length, etc.
 
Ohhhh LOL I'm sorry I didn't even see what I typed
my mind was away. I didn't mean 5 Newtons would bend it 1m
 
Would you get a higher modulus if you used a thicker beam?
It's a material property. How is the modulus defined?

You can also look for other people who've done the same and talked about it.
It's a common enough experiment - done either by vertical deflection by weights or by Timing harmonic motion.
 
I found out my value is very wrong D: I need to recheck my calculations
 
I am so stupid =.= I left off a 10^-8 somewhere in my calculations.

New value which makes sense NOW is 5.10 x 10^7Pa.
 
Sigh again i was wrong I did it over again I got 5,108.1 MPa
 
  • #10
When you have measurements on such a wide variation of scales, it is very easy to misplace lots of zeros :)

You can see from the discussion of accuracy in the article that these can get very big (as much as 56% it says) so you only need the right order of magnitude. "Conclude: Youngs modulus for a wooded meter-rule was experimentally determined to be _____GPa. This agrees to the same order of magnitude as an accepted value of _____GPa given in ref. ______."

If you did errors then you can also comment on how good the agreement was.
 
  • #11
Thank you.
 

Similar threads

Confusion Calculating Young's Modulus
  • · Replies 5 ·
Replies
5
Views
2K
Relationship of Young's modulus and impulse force
  • · Replies 3 ·
Replies
3
Views
2K
What is the Young's Modulus of Aluminum, Steel, and Brass?
  • · Replies 14 ·
Replies
14
Views
3K
Appying a force bar + Young's Modulus + Force Applied
  • · Replies 3 ·
Replies
3
Views
2K
Calculating stress, strain and Young's modulus?
  • · Replies 2 ·
Replies
2
Views
6K
Young modulus (deriving formula)
  • · Replies 7 ·
Replies
7
Views
20K
Basic Stress and Strain question -- Rock on top of a vertical column
  • · Replies 19 ·
Replies
19
Views
2K
Traction/ Compression stress and strain exercise
  • · Replies 1 ·
Replies
1
Views
2K
Log hanging from 2 steel wires. stress/strain youngs modulus
  • · Replies 8 ·
Replies
8
Views
7K
How to Calculate Young's Modulus from a Non-Linear Stress-Strain Graph
  • · Replies 5 ·
Replies
5
Views
3K