Throwing a frisbee and measuring change in mechanical energy

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Homework Help Overview

The discussion revolves around a problem involving the mechanical energy of a frisbee thrown from a height, examining the effects of air drag on its energy as it reaches a lower height. The subject area includes concepts of energy conservation, kinetic and potential energy, and the impact of external forces like drag.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculation of changes in mechanical energy, questioning the impact of air drag and whether to separate velocity into components to analyze the effects of gravity and drag. There is also a reference to a guide's answer that differs from the original poster's calculations.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and questioning the assumptions made regarding the frisbee's height and energy calculations. Some guidance has been offered regarding calculating total mechanical energy, but no consensus has been reached on the correct approach or final answer.

Contextual Notes

There is uncertainty regarding the final height of the frisbee and the accuracy of the calculations presented, as well as a reference to a guide that provides a different answer than the original poster's findings.

sjcorona
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A 75g Frisbee I thrown from a point 1.1 m above the ground with a speed 12 m/s when it has reached a height $.1 m its speed is 10.5 m/s What is the reduction in Emec of the frisbee-earth system because of air drag?


At first I thought Since ΔEmec= Δk+Δu the change is -0.61 J
Then I reasoned that only the kinetic is affected by drag Δk= -1.3 J
Now I'm wondering if I need to split the velocity into x and y components so I can separate the decrease due to gravity and the decrease due to drag? But I don't thinknthats what they want me to do. According to the guide The answer ends up being 0.53 J
 
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Calculate the total mechanical energy at each point.
 
I did that too,Emec2 - Emec1 is still 0.61
 
I don't see how you got that answer (or the guide's answer). What is the final height of the frisbee? Is it 0.1 m?
 

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