q4_8 - Chapter 4 Question#8 Estimate the time required to...

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Chapter 4 Question #8 Estimate the time required to bring a cup (0.3 liter) of water to a boil using a hot plate. The water was taken from the tap at 290K. The label on the hot plate says it is rated at 750W. The Specific heat of water is 4184 J/kg-K. 1) 0-2 minutes 2) 2-5 minutes 3) 5-8 minutes 4) 8-15 minutes
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Chapter 4 Question 8 Answer: This question is designed to provide practice using the specific heat to calculate a temperature change from an energy change. It is also intended to give you some experience estimating and devloping simplified models. For the set-up used in 2002: The basic equation we applied was the first law with no work: U=Q mc T = Power_in * time so time=mc T/Power_in When this is done for the parameters given, time = (0.3kg)(4184J/kg-K)(373K- 290K)/(750J/s) = 139s. However, there were several aspects of the experiment that this does not capture. For example, energy is required to heat the beaker holding the water and the heating coils, some of the heat from the heating coils escapes below and to the
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q4_8 - Chapter 4 Question#8 Estimate the time required to...

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