Calculate Torque for 8N Forces on 0.6m Beam

[Charles W]

Homework Statement

Two 8.0N forces act at each end of a beam of length 0.60m. The forces are parallel and act in opposite directions. The angle between the forces and the beam are 60 degrees.

What is the torque of the couple exerted on the beam?

1. 2.4Nm
2. 4.2Nm
3. 4.8Nm
4. 9.6Nm

Homework Equations

From my understanding: Torque = Fdsinθ, where F is the force and d is the distance from the force

The Attempt at a Solution

I tried to apply the equation (as above) in this example:

Torque = Fdsinθ = 8.0 * .30m * sin(60) ≈ 2.07

However, this isn't one of the given options so I feel I must be doing something wrong.

Any help is greatly appreciated!

 

[TSny]

Don't forget that there are 2 forces.

 

[Charles W]

Don't forget that there are 2 forces.

So do I multiply my answer by two? 2.07 * 2 ≈ 4.15

Therefore is the correct answer rounded up to Option 2. - 4.2Nm?

 

[TSny]

So do I multiply my answer by two?

Yes, the torque due to the couple is the net torque due to both forces.

Therefore is the correct answer rounded up to Option 2. - 4.2Nm?

I think that's correct.

 

[Charles W]

Yes, the torque due to the couple is the net torque due to both forces.

I think that's correct.

Thank you - that makes sense to me now! :)