Newton's Second Law and Friction

AI Thread Summary
The discussion revolves around solving a physics problem involving two blocks, A and B, where block A is on top of block B, and a cable holds block A in place. The key equations include Fnet = ma and the frictional force equation Ff = μN. The user is struggling with the free body diagrams and the net forces, particularly how the frictional forces interact between the blocks and the ground. Clarification is sought on the direction of the frictional forces and the conditions for maintaining constant velocity for block B. Understanding these dynamics is crucial for calculating the necessary horizontal force to drag block B.
am13
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Homework Statement



Block A weighs 1.14 and block B weighs 3.66. Block A rests on top of block B and has a cable connecting it to the wall on its right. The coefficient of kinetic friction between all surfaces is 0.300. Find the magnitude of the horizontal force necessary to drag block B to the left at constant speed if A is held at rest. (See Figure B)

Homework Equations



Fnet = ma
Ff=μN
Fnet = 0

The Attempt at a Solution



I think that I am just getting the forces on the free body diagram wrong. I drew FBDs for block B and block A and got that Fnet = 0, and so the horzontal force plus force friction by block A minus force friction by the ground equals 0. And I got F = FfG-FfA. What have I done wrong?
 

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Hi am13, welcome to PF.
The frictional force acting on A is towards right.
Reaction to this force on B acts towards left.
Applied force on B is towards left.
Frictional force on B acts towards...?
What is the condition for the constant velocity of B?
 
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