Specific Heat Capacity question - Help needed.

  • Thread starter nvidia17
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  • #1
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I'm having a hard time getting my hear around this question. Help would be appreciated as my revision books are not helping. I'm not looking for answers (would be helpful) - just help that will actually be of use to me if I get this question in the real exam.

Two physics teachers are getting hot drinks from a drinks machine. One teacher suggests that the machine must contain a reservoir of hot water. The other reacher says that there isn't room to store water inside the machine. He suggests that the wter must cime from the mains water suply and be heated by a heater in the machine, as it is needed.

The teachers take the following measurements to decde who is correct.
  • Mass of water in cup = 0.20 kg
  • Room temperature = 22 °C
  • Temperature of water in cup = 75 °C
  • Time to fuill cup = 6.0 s
  • (Specific heat capacity of water = 4200 J kg¨¹ °C)

Calculate the energy required to heat the water for one cup.





Energy = ....................................
 

Answers and Replies

  • #2
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The drinks machine is marked "2500 W". Calculate the maximum thermal energy which the heater could supply in the time it takes to fill the cup.



Energy = .....................
 
  • #3
Chi Meson
Science Advisor
Homework Helper
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What is your question, where to start? This is a very straightforward question if you have studied specific heat capacity. You have mass, you have heat capacity, you have a change in temperature, you want to calculate how much heat is reQuired. (That was a hint).
 
  • #4
Astronuc
Staff Emeritus
Science Advisor
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The power supplied by the heater must equal the rate at which the heat or enthalpy of the water changes.

So write an equation which describes this relationship.
 
  • #5
Hi I need help with a question, I need to calculate the total amount of heat necessary to change .75kg of ice at -24*C into water at 107*C. {put heat into kcal}? I need help with this problem.
 

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