Collision Problem: Find Height & Heat Released

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Homework Help Overview

The problem involves a ball of mass 0.1 kg that is free falling from a height of 1 m and collides with the ground, with a coefficient of restitution (k) of 0.5. The questions focus on determining the height the ball will reach after the collision and the heat released during the collision.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the use of energy conservation principles, specifically the equations involving gravitational potential energy and kinetic energy. There are attempts to derive the height after the collision and questions about the correctness of intermediate results and units.

Discussion Status

Some participants are questioning the correctness of the derived equations and the units involved. There is an ongoing exploration of the relationships between the variables, with one participant suggesting a potential error in their calculations. Others are providing feedback on the clarity of the steps presented.

Contextual Notes

Participants note the importance of showing individual steps in calculations to identify errors. There is also a mention of formatting conventions, such as the use of decimal points instead of commas.

Xsnac
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Homework Statement


a ball of mass 0.1 kg, is free falling from the height (h1) of 1 m. hits the ground with a k = 0.5.
##k=\frac{v_2}{v_1}##
A)Height that the ball will reach after the hit.
B)The heat quantity released by collision

Homework Equations


I think ##mgh## and ## \frac{mv^2} {2} ##

The Attempt at a Solution


I found ##h_2## = 0,1 m , is this correct? .
divided the process in 2 steps :
##mgh_1= \frac {mv^2_1}{2}## and found ##v_1=\sqrt{2gh_1}##
and then did the same for the other 2 parts of the "movie"
##mgh_2= \frac {mv^2_2}{2}## and found ##h_2=\frac{v_2^2}{2g} ##
then I just replaced ##v_2## and calculated ##h_2##
 
Last edited:
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Xsnac said:
k=v2v1
I guess that means k=v2/v1.

0.1m is not correct. What did you get as intermediate results?

By the way: decimal point instead of comma in English.
 
mfb said:
I guess that means k=v2/v1.

0.1m is not correct. What did you get as intermediate results?

By the way: decimal point instead of comma in English.
well i found ## h_2 = \frac {k \sqrt{2gh_1}} {2g} ##
 
That equation is wrong (it has wrong units, it cannot work), but if you don't show your individual steps it is impossible to tell what exactly went wrong.
 
mfb said:
That equation is wrong (it has wrong units, it cannot work), but if you don't show your individual steps it is impossible to tell what exactly went wrong.
Ok let's see. after the 4 equations I posted on the first thread I found out ##h_2## with the following steps :
## \frac{mv^2_2}{2}=mgh_2## => ##h_2=\frac{v^2_2}{2g} ## , then I replace ##v^2_2## with ## (kv_1)^2## ok I found the error i think ? ##h_2=k^2h_1## ?? should it be 0,25 ?
 
Last edited:
Xsnac said:
Ok let's see. after the 4 equations I posted on the first thread I found out ##h_2## with the following steps :
## \frac{mv^2_2}{2}=mgh_2## => ##h_2=\frac{v^2_2}{2g} ## , then I replace ##v^2_2## with ## (kv_1)^2## ok I found the error i think ? ##h_2=k^2h_1## ?? should it be 0,25 ?
Yes.
 

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