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Hi This is a really trivial comment in my notes but for some

  • Thread starter D44
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D44
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Hi

This is a really trivial comment in my notes but for some reason I'm not seeing it...

The following image demonstrates the perpendicular distance from an origin to the line of action of the force given as x*sin(x,F). So the moment, M = f*x*sin(x,F) which I understand.

But why is it sin? Why not cos or tan? I understand trig, I just can't see how this is working. Maybe because of the positioning of the angle?

Thanks in advance
 

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  • #2
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You'll need to attach or otherwise link to the image.
 
  • #3
rude man
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Hi

This is a really trivial comment in my notes but for some reason I'm not seeing it...

The following image demonstrates the perpendicular distance from an origin to the line of action of the force given as x*sin(x,F). So the moment, M = f*x*sin(x,F) which I understand.

But why is it sin? Why not cos or tan? I understand trig, I just can't see how this is working. Maybe because of the positioning of the angle?

Thanks in advance
The vector formula for moment is τ = r x F. In your notation, r = x and F = F.

The magnitude of r x F is |r|*|F|*sinθ where θ is the angle between r and F. This is strictly a mathematical definition.
 
  • #4
D44
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Apologies
 

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