Calculating Tension in a Falling 5kg Brick on a Rope | Homework Problem

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Homework Help Overview

The problem involves calculating the tension in a rope supporting a 5kg brick that is accelerating downward at 1.5 m/s². The context includes the application of Newton's second law and gravitational force calculations.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to calculate the tension using the equation T = mg + ma, but expresses uncertainty about the correctness of their approach. Other participants question the reasoning behind the equation used and seek clarification on the original poster's thought process.

Discussion Status

The discussion is ongoing, with some participants affirming the original poster's calculations while others encourage deeper exploration of the reasoning behind the equations used. There is no explicit consensus on the correctness of the solution yet.

Contextual Notes

The original poster expresses concern about potentially missing something in their calculations, indicating a possible lack of confidence in their understanding of the problem setup.

demonslayer42
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Homework Statement


A 5kg brick on a rope is lowered towards the ground. While the brick is accelerating downward at 1.5m/s^2, find the tension in the rope. What is the reaction force to the upward force of tension acting on the brick?

Homework Equations


Sum of F = ma
w = Fg = mg
g = 9.8 m/s^2

The Attempt at a Solution


So basically what I did was drew a diagram.

/\ T
#
#
# a = -9,8 m/s^2
#
#
\/ W = mg = 5.0(9.8) = 49 N

T = mg + ma = 49 + 5.0(-1.5) = 41.5 N

O.k. where did i go wrong? lol I can't figure this out and it's driving me crazy
 
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Doesn't look wrong to me...why do you think it is wrong?
 
Because I always do something wrong...You sure it's correct? I'm just really shocked I got it correct it seems to easy i must be missing something.
 
You noted correctly that T=mg + ma, where a is negative. How did you arrive at that equation? That's the most important part.
 

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