How is the amount of energy dissipated by friction calculated?

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Homework Help Overview

The discussion revolves around calculating the amount of energy dissipated by friction when a block comes to a stop. The subject area includes concepts of energy conservation, potential energy, and kinetic energy in a physics context.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relationship between initial kinetic and potential energy and the final potential energy to determine energy lost due to friction. There are questions about the necessary variables and the assumptions regarding energy loss.

Discussion Status

Some participants have provided insights into the energy conservation principle and how to set up the equation for energy lost. There is an acknowledgment of the need for additional information or sketches to clarify the problem further. Multiple interpretations of the energy loss due to friction are being explored.

Contextual Notes

Participants note that the problem requires expressing energy in terms of variables such as mass, velocity, and height, and there is an emphasis on the assumption that energy loss is solely due to friction.

cmed07
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I need help figuring out the equation for E :

Find the amount of energy E dissipated by friction by the time the block stops. Express your answer in terms of some or all the variables m, v, and h and any appropriate constants.
 
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cmed07 said:
I need help figuring out the equation for E :

Find the amount of energy E dissipated by friction by the time the block stops. Express your answer in terms of some or all the variables m, v, and h and any appropriate constants.
You'll ned to furnish a sketch or more info, and an attempt at a solution, before we can help...
 
Since the problem states "by the time the block stops." we can assume the final energy is purely potential energy.

So one possibility could be finding the initial potential and kinetic energy and subtracting the final potential energy from those.

KEi+PEi-PEf=Energy lost

Then plug in your variables for KE and PE

This is assuming energy is not being lost due to any force other than friction.
 
Sovos said:
Since the problem states "by the time the block stops." we can assume the final energy is purely potential energy.

So one possibility could be finding the initial potential and kinetic energy and subtracting the final potential energy from those.

KEi+PEi-PEf=Energy lost

Then plug in your variables for KE and PE

This is assuming energy is not being lost due to any force other than friction.
Yes, looks very good! You even got the plus and minus signs correct :cool: Now just adapt that to your given problem.
 
Sovos said:
Since the problem states "by the time the block stops." we can assume the final energy is purely potential energy.

So one possibility could be finding the initial potential and kinetic energy and subtracting the final potential energy from those.

KEi+PEi-PEf=Energy lost

Then plug in your variables for KE and PE

This is assuming energy is not being lost due to any force other than friction.

Thanks! This helped me a lot :)
 
cmed07 said:
Thanks! This helped me a lot :)
OK, but just remember (because I forgot!) that total energy can neither be gained nor lost...it is always conserved. What energy is lost due to friction is compensated for by an increase in heat, sound, and other forms of energy.
 

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