Equal Moments at A: Reasoning and Calculation

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The discussion centers on whether two forces have equal moments about point A. The initial reasoning suggests they are equal based on the formula L*cos(30), but this is challenged as incorrect. The correct approach involves using the torque formula τ = rFsinθ, which confirms the moments are indeed equal when calculated properly. Despite the initial misunderstanding, the conclusion reached is that the moments are equal. The conversation highlights the importance of precise terminology and understanding in physics calculations.
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Homework Statement



Do the following have equal moments about A?

moment031.gif


moment032.gif


Homework Equations



T=rf

The Attempt at a Solution



Yes because using L*cos(30), they will be the same?


What is your reasoning?
 
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NoobeAtPhysics said:
Yes because using L*cos(30), they will be the same?

What is your reasoning?

Your reasoning is incorrect ...

τ = r×F

τ = rFsinθ

or τ = r times (component of force perpendicular to line joining A and point of application of force )

So what is τ ?
 
They both use τ = rFsin30 right? That means they are equal! Right?
 
Right...
 
Last edited:
NoobeAtPhysics said:
They both use τ = rFsin30 right? That means they are equal! Right?
"Use" is a strange word there. "Supply" perhaps. Anyway, you asked whether your reasoning was correct, and Tanya S was right in reply, that your reasoning was incorrect (though you got the right answer).
 

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