Re: Gradient measurements

["M.B. and C.M.McDonald" <michael.and.colleen.mcdonald@xtra.co.nz>]

David Martin wrote in message <36692151.0@news.camtech.net.au>...
>What is the conversion formula for our 1 in x form of gradient measurements
>to the percentage system?
>Also, conversion to degrees?


For conversion to/from degrees, the figure to remember is 57.3 (no ... not
42!)
(The formulae hold up to 20-30 degrees depending on the accuracy you want)

1 in x  =  100 / x  %
1 in x  =  57.3 / x  degrees

x  %  =  0.573 x  degrees
x  %  =  1  in  100 / x

x degrees  =  1  in  57.3 / x
x degrees  =  x / 0.573  %


To be more precise, and for steeper slopes :-

Pi  =  4 * atan(1)

1 in x  =  ( 180 / Pi ) * ATAN ( 1 / x )  degrees

x  %  =  ( 180 / Pi ) * ATAN ( x / 100 )  degrees

x  degrees  =  1 in 1 / TAN ( x / ( 180 / Pi ) )
x  degrees  =  100 * TAN ( x * Pi  / 180 )  %

The above are the formulae to use in a spreadsheet, where angles for trig
functions are in RADIANS, not degrees.
You will notice the use of the fraction  Pi / 180  (which is the figure 57.3
in the simpler formulae).  It is the conversion factor for radians to
degrees.

If the slope is measured as  ( 1 in track distance travelled )  instead of
( 1 in horizontal distance travelled )  - which makes a vertical slope 1 in
1 - replace "tan" by "sin".

Sorry for the delayed reply  ... having trouble keeping up with the
newsgroup at present!

Cheers
Michael