Minimum force required to turn over box.

mercredi 1 janvier 2014

Hi,

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

I would like to determine the position, magnitude and direction of the minimum force F required to turn over the box shown in the attachment (width - B, height - H). The (uniform) box is placed on a horizontal plane. The coefficient of friction between the box and the plane is μ.





2. Relevant equations







3. The attempt at a solution

Since τ=r x F, I believe the minimum force would have to be at either D or C (so that r is maximum). I picked C and placed my Fx and Fy there, where Fx=Fcosθ and Fy=Fsinθ and θ is the angle between F and the positive x axis. I was then trying to write the equations for the torques wrt to A. I figured that when the box is turned over, N equals zero and therefore there is no friction. I was then left with two effective forces, namely: F and mg.

The equation I wrote down was:

BFsinθ - FHcosθ-mgB/2=0

Is that correct?




Attached Images





File Type: jpg untitled.JPG (11.5 KB)







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