Free Body Diagrams: Static Equilibrium

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Homework Help Overview

The discussion revolves around determining the force required to maintain static equilibrium for two blocks, each with a mass of 5 kg, on frictionless surfaces. The problem involves analyzing forces in both the horizontal and vertical directions.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of force components and the conditions for static equilibrium. There are attempts to derive relationships between acceleration, force, and the angles involved. Questions arise regarding the calculation of acceleration and the correct interpretation of the angle provided.

Discussion Status

Some participants have offered guidance on how to relate the forces and acceleration, while others are seeking clarification on specific calculations. There is an ongoing exploration of the relationships between the variables involved, but no consensus has been reached on the correctness of the calculations presented.

Contextual Notes

Participants note the importance of the angle in the problem, with one pointing out that the given angle is 20 degrees, which may affect the calculations being discussed.

hunter007
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Homework Statement



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.

1ecfa665f27769be8679c7df4a6cd8af.jpg


Homework Equations



I know I need to find where Fx= 0 and where Fy= 0.

The Attempt at a Solution



Fx = Fcos20
Fy= Fsin20 - 5 kg

Am I even close?
 
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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.
 
Could you explain a little more on how to get a? Once I find that I could find F.
 
mg*sinθ = a*cosθ.
Find a.
 
a = 5(9.8)*tan(30)
= 28.3

F= 28.3(5+5) = 283 N.

Did I do it right?
 
The given angle is 20 degrees.
 

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