[WWcvs] pg: Changed the numerical values of lbf to make it more accurate

[Mike G. v. a. <we...@ma...>]

Log Message:
-----------
Changed the numerical values of lbf to make it more accurate (assuming that lbf is an abbreviation for ft-lbs which I doubt).

Also replaced the conversion factor for pounds with a more accurate figure.

Modified Files:
--------------
    pg/lib:
        Units.pm

Revision Data
-------------
Index: Units.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Units.pm,v
retrieving revision 1.3
retrieving revision 1.4
diff -Llib/Units.pm -Llib/Units.pm -u -r1.3 -r1.4
--- lib/Units.pm
+++ lib/Units.pm
@@ -51,6 +51,7 @@
 # be zero.
 
 my $PI = 4*atan2(1,1);
+#         9.80665 m/s^2  -- standard accelearationof gravity
 
 my %known_units = ('m'  => {
                            'factor'    => 1,
@@ -288,7 +289,7 @@
                            's'         => -2
                           },
                  'lb'  => {
-                           'factor'    => 4.45,
+                           'factor'    => 4.4482216152605,
                            'm'         => 1,
                            'kg'        => 1,
                            's'         => -2
@@ -328,7 +329,7 @@
                            's'         => -2
                           },
                 'lbf'  => {
-                           'factor'    => 1.355,
+                           'factor'    => 1.35582,
                            'm'         => 2,
                            'kg'        => 1,
                            's'         => -2