What is the mass of water used to cool the iron car engine?

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Homework Help Overview

The discussion revolves around a problem in thermodynamics involving the cooling of a car engine using water as a coolant. The scenario includes specific temperatures and the heat exchange that occurs as the engine and coolant cool down to the surrounding air temperature.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relevant formulas for calculating heat transfer and mass, with one participant detailing their calculations for the heat lost by the iron engine and the subsequent heat absorbed by the water. Questions about the correctness of the calculations are raised.

Discussion Status

The discussion includes an initial attempt at solving the problem, with one participant providing detailed calculations. Another participant acknowledges the calculations as acceptable, indicating a level of agreement on the approach taken.

Contextual Notes

Participants emphasize the importance of making an attempt at the problem before receiving help, suggesting a focus on individual effort in the learning process.

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A 2.50 x 10^2 kg iron car engine contains water as coolant. Suppose the temperature of engine is 35 degree celsius when it shut off and air temperature is 10degree celsius. The heat given off by engine and watering it as they cool to air temperature is 4.4 x10^6 J. What is the mass of water used to cool engine?
 
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You must make an attempt at solving the problem before help can offered. What formulas are relevant? What have you tried?
 
gneill said:
You must make an attempt at solving the problem before help can offered. What formulas are relevant? What have you tried?

This is what i did:

Q for iron = mc(tf-ti)
= 2.50 x 10^2 kg x 450 J/kg/°c x (10°c - 35°c)
= -2.813 x 10^6 J

Q for water = 4.4 x10^6 J - 2.813 x 10^6 J
= 1.587 x10^6 J

mass for water = Q / c x (tf-ti)
= 1.587 x10^6 J / 4180 x ( 10°c - 35°c)
= 15.0 kg

Is it right?
 
That looks fine.
 

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