Maximum Static Force before Blocks Slip

AI Thread Summary
The discussion centers on calculating the maximum static force before two blocks begin to slip against each other. A 6.40 kg block rests on a 12.5 kg block, with a frictionless interface between the lower block and the table, while static and kinetic friction exist between the two blocks. The acceleration of both blocks at the point of slipping is 2.0 m/s². Participants suggest starting by determining the normal force and considering the blocks as a single unit just before slipping occurs. The goal is to find the force applied when slipping begins.
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An 6.40kg block rests on a 12.5kg block. The interface between the lower mass and the table is frictionless, but there is friction (static friction μs and kinetic friction μk) between the two blocks. A horizontal force F acts on the upper block and causes both blocks to accelerate. The acceleration of both blocks when they begin to slip is 2.0 m/s2.

fk=μkFN
fs=μsFN

I guess I have no idea how to start with this question. Am I supposed to find the normal force first and work from there? Where do I even go from there? Any help would be appreciated, thanks much!
 
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patchums said:
An 6.40kg block rests on a 12.5kg block. The interface between the lower mass and the table is frictionless, but there is friction (static friction μs and kinetic friction μk) between the two blocks. A horizontal force F acts on the upper block and causes both blocks to accelerate. The acceleration of both blocks when they begin to slip is 2.0 m/s2.

fk=μkFN
fs=μsFN

I guess I have no idea how to start with this question. Am I supposed to find the normal force first and work from there? Where do I even go from there? Any help would be appreciated, thanks much!

You haven't stated what it is you're trying to find...
 
Aw geez, sorry. I have to find the force at the time when the blocks start to slip.
 
patchums said:
Aw geez, sorry. I have to find the force at the time when the blocks start to slip.

Okay, so immediately before the blocks begin to slip they are essentially one large block...
 
Try to imagine by sitting on the lower block. What you see? Where should the force act?
 
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