How Much Force is Needed to Balance a Wheelbarrow Load?

[kathyt.25]

Homework Statement

If the load placed in the wheel barrow weighs 20 N and is 40 cm
from the wheel, what force must be applied to the handles at a
distance of 120 cm in order to balance the load?

Homework Equations

Tau = F r Sin(theta)

The Attempt at a Solution

Im really just guessing on how to do this, but here's my attempt..

Tau of load = (20N)(0.4m)Sin90
= 8N

therefore,
8N = (F)(1.2m)Sin90
6.67N = F --> Thats my answer

 

[Delphi51]

The question is not very clear - what does "40 cm from the wheel" mean? If it means the force of gravity vector from the load center of mass passes a minimum of 40 cm from the center of the wheel, then your solution is correct. Perhaps a better way to understand it is to begin with the big picture:
Sum of Torques = I*α = 0 since there is not angular acceleration.
20*.4 - F*1.2 = 0