Class 1 Lever Experiment: Wrong results

Click For Summary

Discussion Overview

The discussion revolves around an experiment involving a class 1 lever, where a participant reports discrepancies between their experimental results and theoretical predictions based on the lever equation. The focus is on identifying factors that may have influenced the results and understanding the assumptions behind the equation.

Discussion Character

  • Experimental/applied
  • Technical explanation
  • Debate/contested

Main Points Raised

  • The participant expresses confusion about why their experimental results did not align with the theoretical equation for a class 1 lever.
  • Some participants suggest that the equation assumes ideal circumstances and that real experiments often deviate from these conditions.
  • One participant questions whether the distances for "load arm" and "effort distance" were calculated correctly from the fulcrum rather than directly from the ruler.
  • Another participant notes that while moments can be taken about any point, using the midpoint of the ruler simplifies calculations and emphasizes the importance of careful distance measurements.
  • A further comment highlights potential discrepancies due to the actual length of the ruler, suggesting that using the nominal midpoint could lead to measurement errors.

Areas of Agreement / Disagreement

Participants generally agree that the ideal assumptions of the lever equation may not hold in practical experiments, but there is no consensus on the specific factors affecting the participant's results or the best approach to rectify the discrepancies.

Contextual Notes

Participants mention various assumptions related to measurement points and the ideal conditions of the lever equation, but these assumptions remain unresolved and may impact the accuracy of the experiment.

SkyStinger
Messages
2
Reaction score
0
Hey guys, I really need help with this, I do not understand what I did wrong in this experiment.

I had a 30 cm ruler as a beam and some weights of 50 grams, 5 grams and 25 grams. I had a fulcrum which was 17 cm high. As you can see I only have measurements in 50, 5 and 25 grams. So I cut out some random paper, scrunched them into balls to make my lever balance at different lengths.

However, the results the made my lever balance did not match the results I got from the equation:

Effort force = Load force x load arm / effort distance.

Could someone please tell some factors that affected my experiment results and why it didn't match the equation.

Thanks
 
Physics news on Phys.org
The equation assumes ideal circumstances. A real experiment is rarely so simple. You should be able to come up with some ways that the experiment doesn't match the ideal model.
 
Khashishi said:
The equation assumes ideal circumstances. A real experiment is rarely so simple. You should be able to come up with some ways that the experiment doesn't match the ideal model.

Agreed, but what are the factors that makes it not ideal?
 
Sorry if this is a really obvious suggestion but...

Rulers have zero at one end, not at the fulcrum. So when you worked out the "load arm" and "effort distance" did you calculate the distance from the fulcrum or just write down the number on the ruler?
 
Actually, you can take moments about any point. But if you don't take the mid(balance ) point of the ruler, you have to include the weight of the ruler and the calculation is more long winded. For an easier result, you must do as CWatters suggests and relate everything to the mid point. You need to take your distance measurements carefully if you want your sums to 'balance' too.
 
A "30 cm ruler" in the U.S. is very likely 12 inches long -- 30.48 cm. If you were to use the 15 cm marker as the nominal midpoint then your measured moment arms would all be off by 0.24 cm. If you were to use the 15 cm marker as the fulcrum then you would have an additional 0.48 cm of ruler unaccounted-for at one end.
 

Similar threads

High School Lever balancing physics (video game design)
  • · Replies 18 ·
Replies
18
Views
3K
Undergrad Crankshafts, which class of lever
  • · Replies 2 ·
Replies
2
Views
3K
High School Springboard physics questions for diving coach at YMCA
  • · Replies 12 ·
Replies
12
Views
3K
Undergrad 3D Printed Piston | Lower mass = Power
  • · Replies 41 ·
2
Replies
41
Views
5K
High School Can you use hand tools on the moon?
  • · Replies 13 ·
Replies
13
Views
3K
Graduate Can a gyroscope lift a fulcrum (and itself), hinged to the floor?
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad Unraveling the Mystery of "Floating Rule" in an Experiment
  • · Replies 7 ·
Replies
7
Views
2K
High School Why is my experimental spring constant an order of magnitude off?
  • · Replies 4 ·
Replies
4
Views
2K
High School Calculate needed dimensions of table - Center of mass, levers etc
  • · Replies 11 ·
Replies
11
Views
3K
High School Stopping power of rifle slugs
  • · Replies 30 ·
2
Replies
30
Views
3K