Finding mass of a single screw lab No calculations XD

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Homework Help Overview

The original poster is tasked with determining the mass of a single screw using the total masses of five cups, each containing a different number of screws. The cups are of equal mass, and the screws are also assumed to have equal mass. The poster has subtracted the masses of the cups from each other to derive values that they believe relate to the mass of the screws but is seeking a more accurate method.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants inquire about the number of screws in each cup and whether the provided masses include the screws. Some suggest that the method of taking differences between the masses could yield insights into the mass of a single screw. Others discuss the implications of having more unknowns than equations, questioning the feasibility of finding a unique solution with the given data.

Discussion Status

The discussion is ongoing, with various participants exploring different mathematical approaches and questioning the assumptions made about the number of screws and the mass of the cups. Some participants have proposed methods involving differences and sorting, while others express uncertainty about the validity of their calculations and the potential for multiple solutions.

Contextual Notes

Participants note that the problem involves five equations with seven unknowns, suggesting that a unique solution may not be possible without additional measurements. There is also mention of the need for integer values for the number of screws, which complicates the problem further.

  • #31
Trevorr, that is what we have been puzzling over! There appears to be no easy answer for this set of numbers. Usually these problems are carefully crafted so they work out to an exact answer using the differencing technique that gneill describes above (see this one: https://www.physicsforums.com/showthread.php?t=147199 where the answer is 3). In this particular case, the only exact answer is 0.1, which I see as a trivial answer with no meaning. The spreadsheet technique I posted above for dealing with data that includes experimental error is not very satisfactory because there are quite a few "sweet spots" that minimize the average deviation and there is a different best value of m for each value of b.

It appears the question is bad. Perhaps errors have been made at some point in typing the given masses.

It would be interesting to research how Millikan did it. Note: it took him about 20 years to do his experiment.
 

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