Calculating the Spring Constant for a 9.10 kg Mass on a Vertical Spring

AI Thread Summary
To find the spring constant for a 9.10 kg mass compressing a vertical spring by 4.22 cm, the equations F = kx and F = ma are used. The gravitational force is calculated as 89.271 N, leading to the equation k = 89.271 / 0.0422, resulting in k = 2115.43 N/m. The answer needs to be expressed in kN/m, which requires converting the units correctly. The initial submission of 2120 kN/m was incorrect due to improper significant figures, and the exact value was also deemed wrong. Proper unit conversion and significant figure application are crucial for the correct answer.
BHFCBabe
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Homework Statement


When a 9.10 kg mass is placed on top of a vertical spring, the spring compresses 4.22 cm.
Find the force constant of the spring.

Homework Equations


F=kx
F=ma

The Attempt at a Solution


I know that Fgravity should =Fspring so I set the two above equations equal to each other and plug in the proper values.
I will also convert the cm to meters so my answer has the correct units.

9.10(9.81)=k(.0422)
89.271/.0422=k
k=2115.43

It wants the answer in kN/m
I put 2120 first, because I thought it had the right number of sigfigs, but that was wrong.
So then I put in my exact answer which was also wrong.

What am I doing wrong?
 
Last edited:
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BHFCBabe said:

Homework Statement


When a 9.10 kg mass is placed on top of a vertical spring, the spring compresses 4.22 cm.
Find the force constant of the spring.


Homework Equations


F=kx
F=ma


The Attempt at a Solution


I know that Fgravity should =Fspring so I set the two above equations equal to each other and plug in the proper values.
I will also convert the cm to meters so my answer has the correct units.

9.10(9.81)=k(.0422)
89.271/.0422=k
k=2115.43

It wants the answer in kN/m
I put 2120 first, because I thought it had the right number of sigfigs, but that was wrong.
So then I put in my exact answer which was also wrong.

What am I doing wrong?
Hint: kN/m?

AM
 
I realized that about an hour later. Thanks.
 

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