Static friction between two bodies and a surface

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SUMMARY

The discussion centers on the calculation of maximum force applied to box B, which is resting on a surface with box A on top. The static friction between A and B is 40 N, while the static friction between B and the surface is 20 N. The correct maximum force that can be applied to B without causing A to slip is 220 N, accounting for the forces acting on both boxes. The confusion arises from misunderstanding how static friction operates and the net forces involved in the acceleration of the boxes.

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  • #31
nothing is wrong, at least not from where I'm sitting.

in fact I received back a quiz I had 2 days ago, and got 100(A+ in conventional terms, I guess).

Doc Al has been great help in helping me understand it all.

thanks again.
 
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  • #32
the answer given by ur textbook is correct
u can solve the problem if u know seudo force topic
 
  • #33
if u want the block A to be stationary with respect to bolck B.
the net force acting on it must be equal to zero.
fmax a,b = 40
a = 40/5=8
now a seudo opp in direction to this frictional force should act to keep it in rest.
so the block B must move with accelaration of 8
on bolck B frictional force 20N is acting back.
F - fmaxa,b = ma
F- 20 = 160
f = 180N
any doubt contact <personal email removed>
i will explain through a diagram
 
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