Calculating Impulse Without Mass: A Bouncing Ball Lab Dilemma

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Homework Help Overview

The discussion revolves around a lab experiment involving a bouncing ball, where the original poster is tasked with calculating kinetic energy (KE) and impulse without having the mass of the ball provided. The problem is situated within the context of energy conservation and impulse-momentum principles.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate KE by equating potential energy (PE) and KE at the midpoint of the bounce, using the height of the bounce. Some participants question the necessity of mass in the calculations and the implications of the given height. Others suggest reconsidering the relationship between PE and KE, and the definition of impulse in this context.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some guidance has been offered regarding the relationships between energy forms, but there is no explicit consensus on how to proceed with the calculation of impulse without mass.

Contextual Notes

Participants note that the only given information is the height of the first bounce, which raises concerns about the completeness of the problem and its solvability.

Megzzy
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Homework Statement


I am currently working on a lab that deals with a bouncing ball where I need to find the KE and impulse yet I have no mass given.


Homework Equations


PE=mgh
KE=1/2mv
p=mv

The Attempt at a Solution


I have calculated KE by first finding the PE in the middle of the bounce where they will be equal.
So half way from the highest point I calculated PE using PE=mgh. Then assumed KE was the exact same.

I am however confused as to how to calculate impulse since I have no mass, just a KE value.
 
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well what ARE you given?
 
The height of the first bounce was 0.799 m. Therefore half that distance is 0.3995 (Where KE and PE are equal). I then took this is used it in the PE equation. The mass of the ball is not changing however so I don't see that it's needed.
Therefore PE=mgh
PE=0.3995m x 9.8
PE=3.92
Therefore KE=3.92.

I don't know how to get impulse from this.
 
Ep isn't 3.92

if you take Ep=Ek at halfway point then:

mgh=(1/2)mv^2

therefore it is implied that

gh=(1/2)v^2

but it is not implied that Ep=gh...

I don't see what impulse you're looking for? If it's the impulse the ball has when it hits the ground it depends on how squishy the ball is.
 
If all you've been given is the height of the first bounce the question is not answerable.
 

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