Calculating Internal Energy at Victoria Falls

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Homework Help Overview

The problem involves calculating the internal energy produced by water falling over Victoria Falls, with a height of approximately 105 m. The discussion centers around the relationship between potential energy, kinetic energy, and internal energy in the context of this scenario.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate potential energy using the formula PE=mgh but is uncertain about how to determine kinetic energy without temperature information. They question whether internal energy can be found by simply adding kinetic and potential energy.
  • Some participants suggest focusing on the conversion of mechanical energy to internal energy upon impact, questioning the need to calculate temperature changes.
  • There is a discussion about distinguishing between internal energy and macroscopic mechanical energy, with participants exploring how kinetic energy transforms into internal energy when the water crashes.

Discussion Status

The discussion is active, with participants providing guidance on the conceptual understanding of internal energy and its relation to kinetic and potential energy. There is an exploration of different interpretations regarding the calculations needed, but no consensus has been reached on the exact approach to take.

Contextual Notes

Participants note the absence of temperature data and the implications this has for calculating kinetic energy. There is an emphasis on understanding the transformation of energy types rather than focusing solely on numerical calculations.

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Homework Statement


The water passing over Victoria Falls, located along the Zambezi River on the border of Zimbabwe and Zambia, drops about 105 m. How much internal energy is produced per kg as a result of the fall?


Homework Equations



PE=mgh
KE=mc * deltaT

The Attempt at a Solution



PE=33.0067 u * 9.81 * 105= 33998.55134 J
KE= ??

How do I calculate KE if they don't give me the temp of the water?
To get the IE, do I just add KE and PE?

Thanks
 
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I don't see anyone asking you to caculate the rise in temperature (though you could). All you need to figure out is the increase in internal energy. Calculate the amount of mechanical energy converted to internal energy after the water falls. (Hint: What happens to the kinetic energy when the water crashes at the bottom of the falls.)
 
Doc Al said:
I don't see anyone asking you to caculate the rise in temperature (though you could). All you need to figure out is the increase in internal energy. Calculate the amount of mechanical energy converted to internal energy after the water falls. (Hint: What happens to the kinetic energy when the water crashes at the bottom of the falls.)

Internal energy is the total energy (the sum of kinetic and potential energies) attributed to the particles of matter.

So wouldn't I have to calculate PE and KE, then add their values to get the total internal energy?
 
mikefitz said:
Internal energy is the total energy (the sum of kinetic and potential energies) attributed to the particles of matter.
I think you need to be more precise and distinguish internal energy from macroscopic mechanical energy. Read this: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/inteng.html"

So wouldn't I have to calculate PE and KE, then add their values to get the total internal energy?
When the water falls and crashes into the rocks (or still water) its ordered, macroscopic KE is transformed into disordered microscopic internal energy. How much KE does 1 kg of water have at the bottom of the falls?
 
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