Sound Experiment: Dropping 4 Masses from a 3rd Floor Window

[KingNothing]

Hey everybody. We have this extra credit project due friday. The conditions are as such:

We use a 3 meter string and hang 4masses on it with the distance being no less that .5m apart. We can use masses in variations of 50kg, but he suggested we use all 100kg masses.

We drop the string from a 3rd floor window, and the sound of the masses hitting the ground is measured versus time. We use that graph with a program called graphical analysis, and we must achieve a correlation of 98% with a straight line.

Put simply, the time between the sound of each one hitting must be about constant.

I'm not really sure about anything else. We are allowed to use sources such as this fine forum, so I'm thankful for that. What suggestions do you guys have?

Thank you in advance. Love you guys.

Now, my idea was to have the masses arranged so that there is a smaller distance between the ones that will be hitting first and a larger between the last ones.

 

[Claude Bile]

50 kg and 100 kg masses on a string?! Pretty tough piece of string!

Seriously though, have you thought about how you will measure time? Stopwatches probably won't cut it for a correlation of 98%. If you can solve that problem you should be ok.

 

[LURCH]

Originally posted by Decker


Now, my idea was to have the masses arranged so that there is a smaller distance between the ones that will be hitting first and a larger between the last ones.

On the right track, I think. and you can calculate how much longer weights 2 and 3 will be in freefall to determine how much faster each one will be going when it hits, this will tell you how much farther apart they need to be.

Or, you could hold the string perfectly horizontal and drop it. All three weights hit the ground simultaniously (from the lab's inertial frame of reference, of course), so the time interval between 1 and 2 = 0, and the time interval between 2 and 3 = 0. The success of this matheod depends on three main factors; 1) how precisely horizontal can you hold the string? 2) How precisely can you syncronise release of the two ends, and 3) The disposotion of your prof.