# Is this assumption correct? (force vectors and moment)

• June 4th 2009, 11:42 AM
gva0324
Is this assumption correct? (force vectors and moment)
Three forces are applied to a body. They are :

F1 = (4,5) applied at (1,2)

F2 = (2,-1) applied at (3,-1)

F3 = (-3, 2) applied at (-2,1)

i) Find the resultant force

ii) Find the total moment about the origin

Answer: I calculated this and it is -5 Nm

iii) The line of action of R cuts the Y-axis at (0,d). Find d

Question: Can I assume that R = (3,6) is applied at (0,d) and its moment about the origin is - 5Nm? In order to find what d is?

If that assumption is wrong then how do i find d?
• June 5th 2009, 06:26 AM
skeeter
$
(x,y) \times (3,6) = 6x-3y
$

$6x-3y = -5$ is the line of action