Hanging Bridge Lab Work-----ZiTong Cheng

 data：

    

                                                                             data 1

                                                                               data 2

graph：

data 1

data 2

Questions:

1. How should we adjust the masses of objects A and C?
We'll conduct experiments starting with 250g for the first test and then jump to 2kg for the second test. This extreme contrast helps reveal how the system behaves under vastly different loads. The significant mass difference will clearly show how weight changes affect the system's performance.

2. Are the pulleys truly frictionless? How can we determine this?
Our theoretical model assumes frictionless pulleys, but real-world conditions may differ. We can verify this by comparing actual measurements with theoretical predictions. Consistent results at light weights but growing deviations at heavier loads would indicate the presence of friction in the pulley system.

3. What mass increments should we use for object B and how many measurements?
We recommend three crucial measurements: first at 250g, then at 375g (adding half of the previous weight), and finally at 2kg. This progressive approach efficiently captures the system's behavior across different weight ranges while keeping the experiment manageable.

4. How should we estimate measurement uncertainty?
We'll use multiple independent observers to estimate errors. By having different experimenters record measurements separately, we can determine the error range from variations in their readings. This method realistically captures the potential variations in actual operation.

5. What's the proper way to record experimental data?
We should maintain a clear data table including: the mass of object B, the measured center height position, and the estimated error range. For example, we'd record the height measurement at 2kg along with the error range determined from multiple observers, ensuring comprehensive and analyzable data.

6. How should we plot and analyze the results?
Plot the measured height data with error bars on a graph alongside the theoretical prediction curve. If the lines match well at lower weights but diverge at higher weights, it indicates where our theoretical model needs refinement to account for real-world factors.

7. When do theory and experiment agree? When do they begin to differ?
The results should match theoretical predictions at light weights (below 0.5kg), validating our basic model. However, discrepancies will likely appear as weight increases beyond 1kg, suggesting that factors like friction become significant and need to be incorporated into the model.

8. What are the main sources of experimental error?
The primary error sources are: (1) Actual pulley friction not included in the theoretical model, and (2) Rope stretching, especially under heavier loads. These factors combine to affect the accuracy of our final results.

9. What should we report to our supervisor?
Our report should highlight that the theoretical model works well for light loads but requires adjustments for heavier weights. We should recommend incorporating friction coefficients and other practical factors to improve the model's accuracy in real-world applications.

10. Do the experimental results match our predictions?
Yes, for light weights the match is good, confirming our basic theory. However, the differences at heavier weights show that reality is more complex than our initial model. The general conclusion is that the theory provides a good foundation but needs practical adjustments.

11. What additional information is needed for rainforest walkway applications?
factors like humidity's effect on friction and long-term pulley wear patterns, real-world conditions.


Summary：The experiment proves pulley friction matters - light weights match theory (near frictionless), but heavy weights show clear friction effects.