Classes - 12a

12a org meeting

for april 8:

- problems for sections, need solution handouts: text problems

8.8

8.12

8.36

8.66

- Need up-to-date grade sheet by Wed, all work up through April 4. Presumably MQ2 is graded...

- everyone work through MQ3 by Wed.

- produce MQ3 solutions by Friday

- assign project lead contacts

- who's got the chain? Set up force sensor?

- staffing lab room for projects?

- project milestones

- project wiki pages

- who wants eval's?

- booking scibox for finals week.

Projects for 12a, 2014

Feb 18 2014, CWS

Newton's beads links:

Nature piece:

http://www.nature.com/news/physicists-explain-gravity-defying-chain-trick-1.14523

explanation paper: bead_fountain_1.pdf

second paper: chain_fountain.pdf

explanation video: http://www.youtube.com/watch?v=-eEi7fO0_O0

instrumentation:

wideband force transducer

http://www.pcb.com/Products.aspx?m=209C11#.UwNfLXlqtVo

bead chain from McMaster Carr:

http://www.mcmaster.com/#bead-chain/=qqwizc

Another bead chain vendor:

http://rolleasepartsexpress.com/rolleasecontrolchainsandcordloops.aspx

fast CMOS camera for 5K$

http://edgertronic.com/camera/#the-edgertronic

Analog Devices strain gauge wideband signal conditioner

http://www.analog.com/en/other-products/ios-subsystems/5b38/products/product.html

Feb 22, 2014

We purchased #8 and #13 bead chain from McMaster. The ball OD for #8 is 5/32 and #13 is 1/4 inch.

We can use thin-wall stainless steel sleeves to add a rigid section. So we want stainless that is just over 5/32 ID, which is 0.15625".

this vendor sells tubing in 1 foot lengths, $13 per foot. We want size 7X for the #8 bead chain

http://microgroupstore.com/hypodermic-tubing.html

David Morin has hanging and falling chain problems in his text, see page 170. Also worked examples at the end of that chapter

If Biggins is correct, then there should be a measurable variation in the normal force at the bead launch rate, and (easier I suspect) the time integral of the normal force (steady state) should have an additional term of alpha*m*v where m is mass transferred in that interval. In other words there is an additional impulse of alpha*(mv). We should look for this as well as the ac component, which we can average using period folding once rate is known. We can get bead rate from video motion capture or acoustic pickup, see below.

Feb 23 2014

extension ideas:

funnel at top to establish launch boundary conditions

acoustic pickup at bottom to get rate

electrical contact through chain to establish time of first contact at bottom

piezo trigger at bottom to get time of first contact