Conservation of Energey & Kinematics

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Homework Help Overview

The discussion revolves around a lab exercise focused on the Conservation of Energy and its application in kinematics. The original poster describes an experiment involving a spring mechanism to determine how far to stretch it to hit a target 3.75 m away. They mention using a range function to calculate the initial velocity instead of the kinematic equations as instructed in the lab.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to reconcile their method of using the range function with the expected kinematic approach. They express uncertainty about the underlying principles that allowed their method to succeed. Other participants question the distinction between the methods used and clarify that the range function is derived from kinematic equations.

Discussion Status

The discussion is ongoing, with participants exploring the relationship between the methods used and the principles of conservation of energy and kinematics. Some guidance has been offered regarding the connection between the range function and kinematic equations, but there is no explicit consensus on the best approach to explain the results of the experiment.

Contextual Notes

There is a noted discrepancy between the method used by the original poster and the instructions provided by the teacher, leading to questions about the appropriateness of the approach taken. The original poster also expresses confusion about how their method aligns with the expected kinematic equations.

adnama
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Homework Statement



We are working on Conservation of Energy, which for the most part I understand.
In this lab we have a spring that we have to figure out how far we have to stretch it when it's on an apparatus in order for it to land 3.75 m away on a target on the ground. Me and my partner did this and got the target. But we did it differently then the lab told us to ( the teacher didn't care). We used the range function to find the initial velocity we needed. The lab wanted us to use kinematics. Instead of trying to write everything out I scanned

what I have so far with all the work shown:
http://i95.photobucket.com/albums/l149/adnamaplease/Scan100950000.jpg"

And the lab itself w/ a drawing:
http://i95.photobucket.com/albums/l149/adnamaplease/Scan100950001.jpg"

Homework Equations



see work

The Attempt at a Solution



So the question is: What happened? Why does the lab work as it does? (talk about conservation of energy and kinematics)

Since I didn't use kinematics my answer is kinda a guess:

What Happened: Using Conservation of Energy we set up the equation Potential Energy = Kinetic energy + Gravitational Potential Energy. Then we used the Range function to find out what the needed initial velocity was. We found the elastics constant by making the line of best fit and finding the slope. After solving for delta x of the spring we shot the spring and it landed on the desired target.
Why: I'm not sure how to explain how it worked, this is the part I'm lost on
 
Last edited by a moderator:
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I don't understand, you did use kinematics and conservation of energy. The range equation you used was derived from the parabolic kinematic equations.


It most likely worked well enough due to the air resistance being small.
 
When I say kinematics I mean just eh equations my teacher gave us. We never used the range function in class. We were supposed to figure it out with eh regular equations.
 
adnama said:
When I say kinematics I mean just eh equations my teacher gave us. We never used the range function in class. We were supposed to figure it out with eh regular equations.

I'm pretty sure had you started with the general equations you'd have ended up using the equation you used.
 

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