Burning Calories: Calculating Time to Radiate 285 Calorie Donut

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Homework Help Overview

The problem involves calculating the time required for a person to radiate the energy from consuming a 285 Calorie donut, given a power output of 67 W. The context is within the realm of energy conversion and thermodynamics.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the conversion of calories to joules and question whether the calories in the problem refer to kilocalories. There are attempts to relate energy to time using power, with some participants exploring the division of energy by power to find time.

Discussion Status

The discussion includes attempts to clarify the conversion of calories to joules and how to properly relate energy to time using the given power. Some participants provide calculations, but there is no explicit consensus on the correct approach or final answer.

Contextual Notes

There is uncertainty regarding the interpretation of "calories" in the context of food, with participants suggesting that it likely refers to kilocalories. Additionally, there are questions about the correct method to relate energy and time.

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Homework Statement



If a person radiates about 67 W of power at room temperature, how long does it take (h) for a person to radiate away the energy acquired by consuming a 285 Calorie donut?


Homework Equations


i know W=J/s
no clue, i need one that involves time.

The Attempt at a Solution


i've tried 285/67=4.25 sec...but that's wrong...
and i don't think the problem is asking in Kcals
help?
 
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You need to figure out how many joules there are in 285 calories. And I'll bet they are talking about Kcal's. They almost always are when referring to food.
 
ok...
285 Cal=285,000 cal (4.186)= 1.19e6 J

how do i relate it to time though?
do i just divide it by the power?
1.19e6/67=17806 s/60/60=4.95 h
ok thanks
 
Sure. J/(J/sec)=sec.
 

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