Energy transfer question (Use PE=KE or SUVAT ?)

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Homework Help Overview

The problem involves an object falling from a height of 3 meters and seeks to determine its velocity upon impact with the ground. The context includes discussions around using potential energy (PE) and kinetic energy (KE) principles versus SUVAT equations.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants explore two methods for solving the problem: using the conservation of energy (PE=KE) and applying SUVAT equations. There is a noted discrepancy in the results obtained from each method, prompting questions about the validity of using SUVAT in this context.

Discussion Status

Some participants confirm that it is indeed possible to solve the problem using SUVAT equations, while others express uncertainty about the calculations leading to different results. There is a recognition of the need for clarity in the calculations presented.

Contextual Notes

Participants mention the importance of showing work to clarify the reasoning and calculations involved. There is a reference to potential errors in calculations affecting the results.

CannonSLX
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Homework Statement


Object falls from a tree which is 3m above the ground, what is its velocity when it hits the ground ?

Homework Equations


mgΔh=1/2mv2
or
s=vt-1/2at2

The Attempt at a Solution


Using the idea of PE=KE, as the masses cancel out I get an answer of V=7.66ms-1
However I thought that this question can also be done with a suvat equation, I use the same condition which is used for KE [That U=0].

When attempting with suvat I get an answer of 17.15ms-1 why is that ?
 
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CannonSLX said:
When attempting with suvat I get an answer of 17.15ms-1 why is that ?

Hard to tell if you don't show your work!
 
gneill said:
Hard to tell if you don't show your work!
Sorry, I just wanted to know if it was actually possible to be done using suvat ?
 
CannonSLX said:
Sorry, I just wanted to know if it was actually possible to be done using suvat ?
Sure. And the answer should be the same :smile:
 
gneill said:
Sure. And the answer should be the same :smile:
I just tried it again and looked like I forgot how to use my calculator o0), but I did get the same.

Thanks for confirming anyways :)
 

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