- #1

kpx001

- 15

- 0

## Homework Statement

Ok so basiclly I know how to do the problems, but I'm confused when to make the force negative and when to ignore the negative.

forexample: http://yfrog.com/jastaticsprobp

solving part a:

Moment at A = -24*39 -(-14*39) = 2028

notice how i had to do -(-14*39) to compensate for the force going down

VS.

http://yfrog.com/jqstaticsprob2p

where solving for

Moment at xaxis= -230*.250- 230*.210 = -105.8

notice i did not do -(-230*.210)

My assumption?

either keep the direction of force if the problem is 2-D ?? i have no idea, can someone help make this clear? thanks