the reply I wrote was:"What information do we have when we know that a fishing line is 10 pound test?" Is that a pound of mass or a pound of "weight"?
First of all, it is neither; it is the force that the line can exert without breaking (also called the breaking strength). Since it is a force, then the equivalent value in metric is 1.38 newtons.
I think everything I wrote is correct except the numerical value of the result. It should be:
"... the equivalent (of 1 pound force) in metric is 4.45 N."
I make no excuses for my careless error, but it is perhaps of interest to mention what caused me to make it. I used a chart of conversion factors that included the pound of force and also the poundal of force, both units of force in Ye Olde English mix. There being no standard abbreviation for "poundal" that I know of, the author used "pdf" which I misunderstood to mean "pound force" (instead of "poundal force"). Both were given in the table, but I picked the wrong one. (Pound force was abbreviated "lbf" in the table.)
The poundal of force is equal to 0.138 N while the pound of force is equal to 4.45 N. The pound of force in Ye Olde English mix is the force required to accelerate 1 slug of mass at a rate of 1 foot per second squared, while a poundal is the force required to accelerate 1 pound of mass at a rate of 1 foot per second squared. The force of gravity (sometimes called weight) of a 1 pound mass is equal to a force of 1 pound force if the conditions are right (in a gravitational field of a particular, precisely specified strength).
Confusing? Of course it's confusing ... it is Ye Olde English mixture; it's supposed to be confusing. :-)
<><><><><><><><><><><><> Keep it simple; Make it Metric <><><><><><><><><><><><>
Regards, Bill Hooper Fernandina Beach, Florida, USA
