What am I doing wrong in my calculations

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Homework Help Overview

The discussion revolves around a physics problem involving three masses suspended from identical springs in a downward-moving elevator that is accelerating upward. Participants are attempting to calculate the extension of the upper spring from its unstretched length, given specific values for mass and spring constant.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculation of the spring extension, with one participant expressing confidence in their result while questioning significant digits. Others inquire about the configuration of the springs and masses, and whether the springs are connected, which leads to discussions about tension in the upper spring.

Discussion Status

The discussion is active, with participants exploring the implications of the spring configuration and the resulting tension. Some guidance is offered regarding the use of free body diagrams to analyze the forces acting on the masses.

Contextual Notes

There is uncertainty regarding the proper units for the answer and the treatment of significant digits. The configuration of the springs and their connections is also a point of clarification among participants.

aruji73
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What is the distance the upper spring is extended from its unstretched length?
Now, three masses m1 = 3.3 kg, m2 = 9.9 kg and m3 = 6.6 kg hang from three identical springs in a motionless elevator. The springs all have the same spring constant of 229.57N/m

Now the elevator is moving downward with a velocity of v = -2.3 m/s but accelerating upward with an acceleration of a = 4.8 m/s2. (Note: an upward acceleration when the elevator is moving down means the elevator is slowing down.)

What is the distance the upper spring is extended from its unstretched length?
cm


I did

(3.3(9.8+4.8))/229.57=0.20987 m =20.987 cm
 
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aruji73 said:
What is the distance the upper spring is extended from its unstretched length?
Now, three masses m1 = 3.3 kg, m2 = 9.9 kg and m3 = 6.6 kg hang from three identical springs in a motionless elevator. The springs all have the same spring constant of 229.57N/m

Now the elevator is moving downward with a velocity of v = -2.3 m/s but accelerating upward with an acceleration of a = 4.8 m/s2. (Note: an upward acceleration when the elevator is moving down means the elevator is slowing down.)

What is the distance the upper spring is extended from its unstretched length?
cm

I did

(3.3(9.8+4.8))/229.57=0.20987 m =20.987 cm
That looks good to me.

Is there a problem regarding significant digits?
 
Hi I am not sure my answer is supposed to be in cm but I am sure I have done it right puzzling indeed
 
In your problem you have mensioned three springs and three masses. Whether the springs are connected with each other? If yes, who?
 
springs are connected is m1 at top is connected to m2 in middle which is connected to m3 in the bottom
 
So, the spring at the top is supporting, directly or indirectly, all three masses? Won't that increase the tension in it?
 
this is the pic
 

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  • masseshangingfromsprings2smaller.png
    masseshangingfromsprings2smaller.png
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Right, so what is the tension in the top spring? If you're not sure, start with the free body diagram of the bottom mass and work up.
 

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