Calculate elevator acceleration using mass

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Homework Help Overview

The problem involves calculating the acceleration of an elevator based on the weight measurement of a person inside it. The subject area pertains to dynamics and forces, specifically relating to mass, weight, and acceleration in a non-inertial reference frame.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the relationship between the measured weight and the acceleration of the elevator, with some attempting to derive the acceleration using the equations of motion. Questions arise regarding the correct interpretation of forces and units, particularly the distinction between mass and weight.

Discussion Status

The discussion is ongoing, with participants providing guidance on the use of units and the application of equations. There are multiple interpretations of the problem being explored, and while some participants have made attempts to calculate acceleration, there is no explicit consensus on the correct approach or final answer.

Contextual Notes

Participants note the importance of using Newtons for force rather than kilograms for mass, indicating a potential misunderstanding of the concepts involved. There is also mention of the implications of the calculated acceleration, suggesting that assumptions about the scenario may need further examination.

aleah
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Homework Statement



A man with a mass of 65kg is traveling in an elevator and stands on a set of scales, at a given instant the scales measure his weight to be 72kg, find the acceleration of the equation

Homework Equations



f=ma
w=mg
FN =mg+ma[/B]

The Attempt at a Solution


[/B]
I know that the weight with gravity is 65kg and then changes to 72kg when he gets into the elevator because the elevator is pushing back onto him. I also know the elevator is going UP because of the positive change in weight.

Fn = 65kg + 72kg
Fn = 137kg

How do I find the acceleration?
 
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from the last of your equations!
:welcome:
 
I did use the last equation to find that but I am not entirely sure how to get a on its own
BvU said:
from the last of your equations!
:welcome:
 
by the way, you should get used to writing forces in Newtons, not in kg
kg is a unit of mass
 
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Likes   Reactions: aleah
BvU said:
by the way, you should get used to writing forces in Newtons, not in kg
kg is a unit of mass
BvU said:
from the last of your equations!
:welcome:
do I divide the 65N by gravity to find m ? and then divide to get a on its own?
 
so you have fn = ma + mg and you have a scale that registers a force corresponding to m’g = 72 kg, in other words fn = ??
( the 137 you ventured is little high ...)
 
aleah said:
do I divide the 65N by gravity to find m ? and then divide to get a on its own?
yep!
 
thank you! I have the answer as the acceleration being 10.86ms-1
 
that would be a violent affair, if it would be the acceleration of the elevator alone ... :rolleyes:
 
  • #10
aleah said:
with gravity is 65kg and then changes to 72kg
that's right. So the change corresponds to the acceleration
 

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