Work Done by a Spring Force and block problem

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Homework Help Overview

The problem involves calculating the work done by a spring force on a block as it moves between two positions. The context includes the use of a force versus position graph for a spring-block system, with specific values provided for the spring force and displacement.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the potential energy in the spring at different positions and how it relates to the work done on the block. There are attempts to derive the spring constant using given values and equations. Some participants question the appropriateness of using certain equations due to the nature of the spring force.

Discussion Status

The discussion is active with various interpretations being explored. Some participants are attempting to clarify the relationship between potential energy and work, while others are questioning the validity of their equations and assumptions. There is no explicit consensus on the approach to take.

Contextual Notes

Participants are grappling with the implications of a non-constant force and the use of a graph to inform their calculations. There is uncertainty about how to accurately determine the spring constant and apply it to the problem.

soul5
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Homework Statement



http://edugen.wiley.com/edugen/courses/crs1650/art/qb/qu/c07/pict_7_36.gif

gives spring force Fx versus position x for the spring–block arrangement

http://edugen.wiley.com/edugen/courses/crs1650/art/qb/qu/c07/pict_7_11.gif


The scale is set by Fs = 160 N. We release the block at x = 16.0 cm. How much work does the spring do on the block when the block moves from xi =+8.0 cm to x=+7.0 cm


Homework Equations



Fs = -kd

W = Fd

The Attempt at a Solution



Fs/d = k

160N/0.16m = k

1000 = k

kd = F

1000*1m = 1000N

1000N * 1m = W

W = 1000J


I don't know how to this question please help.
 
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When it is stretched to 8 cm how much PE is in the spring?

As it moves back to 7 cm how much potential energy is in the spring?

Isn't the difference then the Work that went to kinetic energy?
 
I disagree with your equations. Force isn't constant, so I don't think you can use W = Fd

Edit: Actually, I may be wrong... I didn't notice that graph you posted up top. I've never seen a spring problem set up with a graph like that before. Disregard this post. :-p
 
LowlyPion said:
When it is stretched to 8 cm how much PE is in the spring?

As it moves back to 7 cm how much potential energy is in the spring?

Isn't the difference then the Work that went to kinetic energy?

PE is just PE = 1/2kx^2

but how do we find k?


160N/0.16m = k

?
 
soul5 said:
PE is just PE = 1/2kx^2

but how do we find k?


160N/0.16m = k

?

That's what I would use.

F = kx so ... why not? The graph says it's linear.
 

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