1.calculate the speed of the bob at the next-to-last spark mark and the d/t for the bob at the last spark mark

Question

1.calculate the speed of the bob at the next-to-last spark mark and
2.the d/t for the bob at the last spark mark
3.calculate the uncertainty in the d/t value for the last visible point

Using diagram
http://img524.imageshack.us/my.php?image=bobxt8.jpg

Answer 1

I get
y(t)=450*t^2-3.75*t inches as the best fit to the data
and v(t)=900*t-3.75 inches/second

Looking at just the next to last and point previous to that
the average speed between is 101.25 in/sec
calculated is also 101.25 using the times and v(t)

at the last point it is146.25 in/sec
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