Need help with tension acceleration problem

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Homework Help Overview

The problem involves a block on a table and another block hanging from a pulley, with a focus on calculating acceleration and tension in the system. The scenario assumes a massless pulley and neglects frictional effects.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss applying Newton's second law to the blocks, questioning how to account for the forces acting on each block. There are inquiries about the interpretation of the weight of the blocks and the implications for their motion.

Discussion Status

Some participants have suggested identifying all forces acting on the blocks as a starting point. There is an ongoing exploration of how the forces interact and whether the blocks can accelerate given their weights. Multiple interpretations of the problem are being considered.

Contextual Notes

Participants are navigating assumptions about the system, including the nature of the forces involved and the implications of the massless pulley. There is a specific mention of the gravitational force acting on the blocks and the need to clarify the relationship between the weights and the tension in the rope.

PhunWithPhysics
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Block sitting on table is 442 N , there is a pulley at the end of table with another 185 N box hanging from a rope that goes through the pulley and attaches to the first box on table. The pulley is massless , I need help finding the acceleration , and the tension...It says ignore all frictional affects and assume the pulley is massless?
 
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PhunWithPhysics said:
Block sitting on table is 442 N , there is a pulley at the end of table with another 185 N box hanging from a rope that goes through the pulley and attaches to the first box on table. The pulley is massless , I need help finding the acceleration , and the tension...It says ignore all frictional affects and assume the pulley is massless?
What do you mean by the first block being 442 N? Does this mean mg = 442 N?

AM
 
It just says the (weight) of the block on the table is 422 (N)ewtons
 
All you need to do is apply Newton's second law to each block and realize that the blocks will accelerate together. You know the masses of the blocks in terms of their weight and the gravitational acceleration. What are the forces acting on each block?
 
how can they be accelerating

How can they be accelerating if the block on top has more force applied to it than the block hang off the table? wouldn't they just sit there? How do you apply Newtons 2nd law to find the tension of the rope. Box 2 is offsetting box one isn't it?
 
please help

I know I need to apply Newtons 2nd law to the boxes but how do i do that?
 
Well, you should start by identifying all the forces acting on each box. That's always how you apply Newton's 2nd law.
 
There's a caveat (which is the fun of this problem) though:
Don't assume that there is simply 185 N pulling on the bloc on the table ! Call the force transmitted through the rope (= the tension) F and work on from there.

cheers,
Patrick.
 
A massless tense rope pulls inward at each end
with Forces that have same absolute value.

Horizontal motion is independent of vertical motion,
(ie, the 442 N is opposed by the F_N by table).
 

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