# Free Body Diagrams: Static Equilibrium

by hunter007
Tags: body, diagrams, equilibrium, free, static
 P: 3 1. The problem statement, all variables and given/known data Blocks A & B each have mass 5kg, and all contact surfaces are frictionless. Determine the force F needed to keep the blocks in static equilibrium, and the forces on all contact surfaces. 2. Relevant equations I know I need to find where Fx= 0 and where Fy= 0. 3. The attempt at a solution Fx = Fcos20 Fy= Fsin20 - 5 kg Am I even close?
 HW Helper P: 4,430 Hi hunter007, welcome to PF. When you apply force F to the systemis, the acceleration of the system is a = F/(Ma + Mb)..........(1). It is parallel to the ground. Since block A is not attached to the block B, due the inertia, it will experience an equal and opposite acceleration. The block A will remain rest when component of the weight of the block A balances the component of the acceleration. Equate these components and find a. Put this value in equation(1) to get F.
 P: 3 Could you explain a little more on how to get a? Once I find that I could find F.
HW Helper
P: 4,430

## Free Body Diagrams: Static Equilibrium

mg*sinθ = a*cosθ.
Find a.
 P: 3 a = 5(9.8)*tan(30) = 28.3 F= 28.3(5+5) = 283 N. Did I do it right?
 HW Helper P: 4,430 The given angle is 20 degrees.

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