MathCAD Units Help

Forum|Forum|13 years ago
March 4, 2013
3 replies
30496 views

I am using MathCAD Prime 2.0 for design calculations for a building I am engineering. I am fairly new to MathCAD, only learning a little about it in college. However, I am running into a units issue when calculating pounds per linear foot (lb/ft) to just pounds (a point load). I am taking 480 PLF * 4 ft, the feet should cancel out and you are left with just pounds. MathCAD is spitting out a lb*f, like the units for a moment. When I go to change the units to just pounds then it changes my units to (ft/s^2)*lb? Please explain to me what is going wrong here. See below for a screen shot:

Please note that the answer is correct, 1920 pounds is the right answer. Just the wrong units.

Thank you in advance,

Jon Recknagel | Structural Designer

Other

Best answer by ptc-4992678

I just answered my own question. A "lbf"= a pound force. It seems like they could have just left it at "lb" we are all aware that pounds is a force. Just my opinon I guess. Thanks anyway.

P

ptc-4992678

AuthorAnswer

1-Visitor

I just answered my own question. A "lbf"= a pound force. It seems like they could have just left it at "lb" we are all aware that pounds is a force. Just my opinon I guess. Thanks anyway.

R

RichardJ

19-Tanzanite

It seems like they could have just left it at "lb" we are all aware that pounds is a force.

The pound is a unit of mass, not force.

P

ptc-4992678

Author

1-Visitor

I would disagree....Pounds (lb) is not a mass. Pounds is a force. F=mg, due to gravity.

B

BillWadsworth

10-Marble

The "lbf", pounds force is there to differentiate between pounds mass, which is just "lb". Something which matters greatly when doing dynamics, rather than statics.