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Dynamics- No Friction

  • Thread starter hsphysics2
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  • #1
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Homework Statement



Find the normal force in terms of g, m, θ and α. There is no friction. a=0, θ≠α

See first attachment for diagram


Homework Equations



Fx=max

The Attempt at a Solution



I drew a free body diagram including the forces; normal, mg, and |FA| (See second attachment) I'm not sure if this is complete as I don't know where α would be part of it.

However I did start with this,

η-mgcosθ=0
η=mgcosθ
mg=η/cosθ (eq'n 1)


Fx=max
|FA|-mgsinθ=max (sub eq'n 1 in)
|FA|-(η/cosθ)sinθ=max
|FA|-(ηsinθ/cosθ)=max
 

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Answers and Replies

  • #2
199
15

Homework Statement



Find the normal force in terms of g, m, θ and α. There is no friction. a=0, θ≠α

See first attachment for diagram


Homework Equations



Fx=max

The Attempt at a Solution



I drew a free body diagram including the forces; normal, mg, and |FA| (See second attachment) I'm not sure if this is complete as I don't know where α would be part of it.

However I did start with this,

η-mgcosθ=0
η=mgcosθ
mg=η/cosθ (eq'n 1)


Fx=max
|FA|-mgsinθ=max (sub eq'n 1 in)
|FA|-(η/cosθ)sinθ=max
|FA|-(ηsinθ/cosθ)=max
look at the given information carefully. It tells you that acceleration, a=0, that is the body is in equilibrium so all the force balance out.
So essentially Fnet=0

Balance out forces in both directions. And remember that FA acts at an angle α (alpha), so appropriately use FA*cos(α) or FA*sin(α) and balance out the forces.

I hope it helps
 
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