# Dynamics- No Friction

1. Oct 8, 2013

### hsphysics2

1. The problem statement, all variables and given/known data

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

2. Relevant equations

Fx=max

3. 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.

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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2. Oct 8, 2013

### NihalSh

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