I am lost, how do I find tension of a rope given A and M?

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Homework Help Overview

The problem involves determining the tension in a rope used to lower a bucket with a specified mass and acceleration. The context is rooted in classical mechanics, specifically applying Newton's laws of motion.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of Newton's second law and the role of free body diagrams. Questions arise about the net forces acting on the bucket and the relationship between tension and weight. Some participants express uncertainty about their calculations and the correct interpretation of forces.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the concepts of tension and net forces. Some guidance has been offered regarding the formulation of equations and the interpretation of acceleration direction, but no consensus has been reached on the correct approach or solution.

Contextual Notes

Participants are working under the assumption that air resistance is negligible and are trying to reconcile their calculations with the principles of Newton's laws. There is also a noted confusion regarding the signs of the forces involved.

Dante
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Homework Statement


A rope is used to lower a 1.1 kg bucket into a well at an acceleration of 1.9 m/s2. Determine the tension in the rope (in Newtons). Assume that air resistance is negligible and the acceleration due to gravity is -9.8 m/s2. Take the positive direction to be upward.

Homework Equations


Newtons 2nd law, A=Fnet/Mnet
T= m (g-a)

The Attempt at a Solution



-1.9 m/s2 = X/1.1 = -2.09N (wrong)
1.1 (-9.8-1.9) = -12.9N (Unsure if right/wrong)

I am lost, I am suppose to use Newtons 2nd law equation but it makes no sense, please help.
 
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Have you drawn a free body diagram? If T is pointing upward and g is pointing downward, what is the net external force on the bucket?
 
Chestermiller said:
Have you drawn a free body diagram? If T is pointing upward and g is pointing downward, what is the net external force on the bucket?
I did draw a free body diagram, hopefully correctly. The weight would be pulling it down making the tension to pull up causing the net external force to be 0 since they cancel each other out, right? If I plugged 0 into the equation for the net force then what would I solve for, since there would be no X?
 
Okay, so the tension and weight do not equal each other, instead they add up to equal the net force, correct? Meaning if I use that equation to find the net force, I then add the weight to it to find the tension? Meaning it would be -2.09 + 1.1kg = .99N?
 
Let T be the upward tension, and mg be the downward force of gravity on the bucket (i.e., its weight). The net of these in the upward direction is T-mg. If a is the upward acceleration, what is Newton's second law written in terms of these parameters? In this problem, is "a" positive (upward) or negative (downward)? What does the force balance you wrote down give you for the tension in the rope?

Chet
 

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