What will the FBD of 2 blocks being pulled look like?

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Homework Help Overview

The discussion revolves around the free body diagrams (FBDs) of two blocks, Block A and Block B, where Block A is on top of Block B. Both blocks have equal mass and size, and Block B is being pulled at a constant velocity while experiencing friction with the table. Participants are exploring the forces acting on each block and the relationship between them.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to identify the forces acting on both blocks, including gravitational forces, normal forces, and frictional forces. Questions are raised about the nature of the friction between the blocks and whether they are moving relative to each other. There is also a focus on the implications of the system's acceleration.

Discussion Status

Some participants have provided their attempts at drawing the FBDs, while others are encouraging further exploration and clarification of the concepts involved. There is an ongoing dialogue about the assumptions regarding the motion of the blocks and the forces acting on them.

Contextual Notes

Participants are reminded to post their own attempts before seeking help, and there is a focus on ensuring that all relevant forces are considered in the FBDs. The discussion is framed within the context of homework rules that emphasize individual effort and understanding.

lyn83716
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Homework Statement



Block A is on top of Block B, both are of equal mass and size. Block B is being pulled by a hook at a constant velocity. There is friction between the table and block B.

Homework Equations


[/B]
What will each FBD look like? Is there friction between Block A and Block B?

The Attempt at a Solution



What are the downwards forces acting on the bottom block (B)? Is it gravity as well as the normal force of the top block? Do those two added = the normal force of Block B?

Block A FBD:
-force of gravity of block a (Fga) pointing downwards which equals to the force of normal of block a pointing upwards(Fgn)
-friction between block a and block b? i don't know

Block B FBD:
-force of gravity pointing downwards, force of A on B pointing downwards
-normal force of b pointing upwards
-applied force pointing fwd
-force of kinetic friction pointing backwards
 
Last edited:
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lyn83716 said:
What will each FBD look like?
You need to post your own attempt first, as per forum rules.
 
Hi lyn83716,

Welcome to Physics Forums.

Your post is all questions but with no attempt at solution(s) or thoughts on what you think will happen. Can you perhaps try to draw what you think the FBDs for the blocks will look like and show us so that helpers can critique the result (tell you where you're right and what might be incorrect)?
 
lyn83716 said:

Homework Statement



Block A is on top of Block B, both are of equal mass and size. Block B is being pulled by a hook at a constant velocity. There is friction between the table and block B.

Homework Equations


[/B]
What will each FBD look like? Is there friction between Block A and Block B?

The Attempt at a Solution



What are the downwards forces acting on the bottom block (B)? Is it gravity as well as the normal force of the top block? Do those two added = the normal force of Block B?

Attempt:

Block A FBD:
-force of gravity of block a (Fga) pointing downwards which equals to the force of normal of block a pointing upwards(Fgn)
-friction between block a and block b? i don't know

Block B FBD:
-force of gravity pointing downwards, force of A on B pointing downwards
-normal force of b pointing upwards
-applied force pointing fwd
-force of kinetic friction pointing backwards
 
haruspex said:
You need to post your own attempt first, as per forum rules.
I posted my own attempt in the replies
 
gneill said:
Hi lyn83716,

Welcome to Physics Forums.

Your post is all questions but with no attempt at solution(s) or thoughts on what you think will happen. Can you perhaps try to draw what you think the FBDs for the blocks will look like and show us so that helpers can critique the result (tell you where you're right and what might be incorrect)?

I posted the attempt in the reply
 
lyn83716 said:
-friction between block a and block b? i don't know
Are blocks a and b moving with respect to each other, or is block a moving along with block b? Is the system accelerating?
 
lyn83716 said:
Attempt:

Block A FBD:
-force of gravity of block a (Fga) pointing downwards which equals to the force of normal of block a pointing upwards(Fgn)
-friction between block a and block b? i don't know

Block B FBD:
-force of gravity pointing downwards, force of A on B pointing downwards
-normal force of b pointing upwards
-applied force pointing fwd
-force of kinetic friction pointing backwards
Next step is to turn those into equations of the form ΣF=ma.
 

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