Home & Garden1 min ago
Answers
Best Answer
No best answer has yet been selected by newpotato. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.
-- answer removed --
-- answer removed --
A reasonably simple formula is L = pi*N*(D+d)/2 where N = (D-d)/(2*t) is the number of wraps of tape of thickness t on a roll of diameter D (when full) around a core of diameter d. The formula represents the average of two estimates using the sum of circumferences of concentric circles (inside vs. outside diameters based on t). The summation formula 1+2+3+...+N = N*(N+1)/2 is needed to develop each estimate.
Or Google Calculating Length of Spiral
Or Google Calculating Length of Spiral
Count the number of bubbles in one unit length.
With a pin, pop each bubble in the roll individually keeping a tally, then divide the total number of pops by the number of bubbles counted in your reference unit length, the quotient being equal to the length of the roll in the unit length originally chosen.
With a pin, pop each bubble in the roll individually keeping a tally, then divide the total number of pops by the number of bubbles counted in your reference unit length, the quotient being equal to the length of the roll in the unit length originally chosen.
jomifl
Measure the diametre of the roll, measure the diametre of the tube it is rolled on, add the two together, divide by 2 and multiply by 3.142. This gives the average length of each turn/layer. Multiply this by the number of layers.
10:30 Fri 14th Feb 2014
Jom, Your formula works if we assume each layer is of uniform thickness. In practice the inner (shorter) layers are more compressed and so most layers will be somewhat shorter than the 'average' length assumed by your formula. Perhaps using the numerically rather than the calculated physically central layer as the one assumed to be of 'average' length would produce a more accurate result.
gingejbee, There's no need to unroll in order to count the number of bubbles on the exposed outermost layer, the length of which can be measured with a flexible tape or nearly approximated by multiplying the outside diameter of the roll by pi. If one is adverse to popping all of the bubbles, one need only count how many rows there are by counting the bubbles that appear along the exposed edge of the roll. Dividing the total number of bubbles along the exposed edge by the number of such bubbles along the edge of the outer most layer provides the multiple of the length of the outside layer to determine the total length of the roll.
Note: Measuring the diameter/circumference of the sheet as opposed to that around the protruding bubbles will improve the accuracy of your results.
Measure the diametre of the roll, measure the diametre of the tube it is rolled on, add the two together, divide by 2 and multiply by 3.142. This gives the average length of each turn/layer. Multiply this by the number of layers.
10:30 Fri 14th Feb 2014
Jom, Your formula works if we assume each layer is of uniform thickness. In practice the inner (shorter) layers are more compressed and so most layers will be somewhat shorter than the 'average' length assumed by your formula. Perhaps using the numerically rather than the calculated physically central layer as the one assumed to be of 'average' length would produce a more accurate result.
gingejbee, There's no need to unroll in order to count the number of bubbles on the exposed outermost layer, the length of which can be measured with a flexible tape or nearly approximated by multiplying the outside diameter of the roll by pi. If one is adverse to popping all of the bubbles, one need only count how many rows there are by counting the bubbles that appear along the exposed edge of the roll. Dividing the total number of bubbles along the exposed edge by the number of such bubbles along the edge of the outer most layer provides the multiple of the length of the outside layer to determine the total length of the roll.
Note: Measuring the diameter/circumference of the sheet as opposed to that around the protruding bubbles will improve the accuracy of your results.
Related Questions
Sorry, we can't find any related questions. Try using the search bar at the top of the page to search for some keywords, or choose a topic and submit your own question.