We had to conduct a similar practice to Millikan's oil drop experiment in class.

This is the situation:

 

There are 10 bags each containing a different amount of small marbles of the same mass. There is also one big marble of different mass to the small marble added to each bag. Each bag is massed and that mass is given to us. Now through techniques similar to those of Millikan, we must:

 

1. Determine the mass of one SMALL marble.

2. Determine the number of SMALL marbles in each bag.

 

Does anyone have any suggestions in terms of what method to use? I have one method that works in theory but is prone to many errors and discrepancies in the result. This method does not involve any mathematical formula or physics concepts so any advice that does incorporate math and physics is preferred. Thanks!

Well you are given a bunch of masses. You must find a number that you can subtract from all of those masses that gives you 10 differences with one common factor. I dont know how to do that quickly, if I were doing that I'd make guesses about the size of the marbles then narrow my guesses using trial and error. I'd bet I could do it pretty quickly, if not elegantly.

You could try figuring out a series for the mass.

Can you come up with an equation that would describe the mass of a bag, in terms of m and M (the masses of the small and large marbles)?

If M is the mass of the large marble, m is the mass of a small marble, and n is the number of small marbles then we can define the total mass, x, as:

 

[math]x=M+nm[/math]

 

What are the masses of the ten bags? I would like to see if I can figure this problem out for myself.

If M is the mass of the large marble' date=' m is the mass of a small marble, and n is the number of small marbles then we can define the total mass, x, as:

 

[math']x=M+nm[/math]

 

What are the masses of the ten bags? I would like to see if I can figure this problem out for myself.

 

If you do, please don't post the solution until rickjames has attempted it.

I won't it just sounds like an interesting project and I want to see if I can get it.

Hey, here are all and only values we were given:

 

Bag 1 - 31.5g

Bag 2 - 61.5g

Bag 3 - 79.5g

Bag 4 - 49.5g

Bag 5 - 86.7g

Bag 6 - 44.1g

Bag 7 - 18.3g

Bag 8 - 143.0g

Bag 9 - 121.5g

Bag 10 - 229.5g

 

I see you comeup with a pretty general formula. The problem we faced when using algebra is an uncontrollable number of unkwown variables; hence, we resorted to a technique that was not as a bad as trial and error but fairly prone to errors as well. GL!

I think we had the exact same thing posted a while ago.

Hmm, just did a quick search and couldn't find it. Link?

Hmm, just did a quick search and couldn't find it. Link?

Try http://www.scienceforums.net/forums/showthread.php?t=18473&highlight=oil+drop

I threw some numbers around but I think there is information that wasn't given in order to solve this problem. Were there any other instructions included with this project that might have some missing info.

It is correct that there is not enough information given to solve this problem using math and algebra but rather rely on some of Millikan's methods and common sense. However, let's say we have found the mass of a small marble, is there anyway mathematically to find the mass of the bag + large marble combined (since we need this to find how many small marbles are in each bag).