What is k for the bottom spring?

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The discussion centers on calculating the spring constant (k) for a vertical spring when a 5.0-kg block is lowered onto it. Initially, the scale reads 49.1 N before contact, indicating the weight of the block. When the scale reads 32 N after compressing the spring by 30 mm, the calculation for k is presented as k = 32 N / 0.03 m, resulting in 1066.7 N/m. Participants debate the correct interpretation of forces acting on the block, emphasizing that both the scale and the spring exert upward forces while gravity pulls downward. Clarifications are sought regarding whether to add or subtract these forces in the calculations.
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Homework Statement


A 5.0-kg block suspended from a spring scale is slowly lowered onto a vertical spring.
Part A: What does the scale read before the block touches the vertical spring?
(answer =49.1N)
Part B: If the scale reads 32 N when the bottom spring is compressed 30 mm, what is k for the bottom spring?

Homework Equations


F=kx

The Attempt at a Solution


K=32/0.03= 1066.7N/m
 
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So would 32 N be the force the block exerts on the bottom spring ?
 
BvU said:
So would 32 N be the force the block exerts on the bottom spring ?
thats what i interpret from the question, is that not correct?
 
If the scale reads 32 N, and ##g## times the mass is 49.1 N ...
Draw a diagram of the forces on the block.
 
BvU said:
If the scale reads 32 N, and ##g## times the mass is 49.1 N ...
Draw a diagram of the forces on the block.
Both forces are acting down so would it be (32+49.)1/0.03=2703
 
The scale is pulling the block up
The bottom spring is pushing the block up
The Earth is pulling the block down
Fnet = ma and the block is not accelerating
 
BvU said:
The scale is pulling the block up
The bottom spring is pushing the block up
The Earth is pulling the block down
Fnet = ma and the block is not accelerating
Would it still not be what I did earlier
 
No.
 
BvU said:
No.
why? what is the mistake, should the forces be subtracted
 
  • #10
upload_2016-11-1_20-13-51.png
Draw the forces the scale and the spring exert. Which way do they point ?
 
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