A steel bar is heated in a furnace until it reaches 2000oF. The blacksmith observes that it cools to 1500oF in 15 minutes. It needs to be hammered into shape before it gets within 500oF of the room temperature (100oF) before it gets too cold to be shaped properly. After pulling out the steel bar from the furnace, how long does the blacksmith have before it needs to be reheated? Assume that Newton's law of cooling is applicable.

A steel bar is heated in a furnace until it reaches 2000oF. The blacksmith observes that it cools to 1500oF in 15 minutes. It needs to be hammered into shape before it gets within 500oF of the room temperature (100oF) before it gets too cold to be shaped properly. After pulling out the steel bar from the furnace, how long does the blacksmith have before it needs to be reheated? Assume that Newton's law of cooling is applicable.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.26P

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