Moment Arm: Determine Torque Vector & Qty

[Pinon1977]

Homework Statement

I'm trying to determine the torque vector and quantity of said vector per the sketch attached.

Homework Equations

T=fd[/B]

The Attempt at a Solution

T = 100 lbs x 2 f2f
T= 200 ftlbs

But my real question is where is that Force being applied at is it the attachment point to the axle or is it relative to its position in space and the vector would be straight down?

 

[haruspex]

where is that Force being applied

The weight acts at the mass centre of the mass, so you would draw the force vector straight down from there. This is important for determining the torque it has about the axle, but for the purpose of figuring out the linear force at the axle the line of action does not matter, only the direction.

 

[Pinon1977]

Ok, noted. So the 200ft lbs in this instance would be twisting the stationary axle in a CCW direction? Even though its attached to the opposite side of the acting force?

 

[haruspex]

Ok, noted. So the 200ft lbs in this instance would be twisting the stationary axle in a CCW direction? Even though its attached to the opposite side of the acting force?

Yes. The path the rigid member takes from axle to point of application of force is irrelevant. You could make the member an entire disc centred on the axle.