Finding ratio of masses of two blocks

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Homework Help Overview

The problem involves two crates stacked on top of each other, with specific coefficients of static friction between the crates and the floor. A force is applied to the top crate, and the goal is to find the ratio of their masses based on the conditions of motion.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between the frictional forces acting on the boxes and the conditions required for them to move together. There are inquiries about the reasoning behind the necessity for one frictional force to exceed another.

Discussion Status

Some participants have offered guidance on setting up inequalities based on frictional forces, while others emphasize the importance of understanding the forces acting on the lower box. The discussion is ongoing, with various interpretations being explored.

Contextual Notes

There is a lack of specific equations provided by the original poster, and the discussion hints at the need for a deeper understanding of the forces involved in the scenario.

RoboNerd
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Homework Statement


  1. Two crates are stacked on top of each other on a horizontal floor. The coefficient of static friction between Box A and Box B is 0.6. The coefficient of static friction between Box A and the floor is 0.2. A force of 100 N is applied parallel to the floor on Box B. The boxes move together along the floor. The ratio of the mass of Box A to Box B is possibly
  1. 1) 5:1
  2. 2) 5:2
  3. 3) 4:1
  4. 4) 3:1
  5. 5) 1:2

Homework Equations



none so far

The Attempt at a Solution


Hi people. I was trying to figure out how to solve this problem, but I do not even have any hints of an idea so far. Could anyone please help me gets started?
Thanks in advance!
 
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For the boxes to move friction between A and B must be greater than between A and the floor.

Write equations for both and set up that inequality. Rearrange.
 
CWatters said:
For the boxes to move friction between A and B must be greater than between A and the floor.

Why is this so?
 
Think about how the applied force is transmitted to the lower box.

Drawing a FBD for the lower box may help.
 
You posted one or two similar questions and they all depend on you understanding the forces acting on the lower box.
 

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