Time for Hot Water to Cool -- Calculation....

In summary, the conversation is about how to calculate the time for boiling water to cool off in a given container with constant temperature and airflow. The speaker suggests using observations and plotting them on a chart to predict the rate of cooling. They also mention considering Newton's Law of Cooling to understand the mechanisms causing heat loss.
  • #1
aiop
38
0
The title says it all. I would like to know how to calculate the time for boiling water to cool off. Assuming the temperature of the room is not changing and there is a constant degree of air flow over the water. Really I would just like to know how to go about calculating this.

Thanks in advanced,
Aiop
 
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  • #2
aiop said:
The title says it all. I would like to know how to calculate the time for boiling water to cool off. Assuming the temperature of the room is not changing and there is a constant degree of air flow over the water. Really I would just like to know how to go about calculating this.

Thanks in advanced,
Aiop

what have you done so far to work this out ?
 
  • #3
Really, the answer has more to do with the container that the water is in and the starting conditions (volume and temperature). It's an engineering question.

The surface areas presented by the sides of the container, the surface area at the top and the thermal conductivity of the materials will have a large effect and not one that can be easily calculated given the variety of materials and designs.

For a specific container, if temperature and airflow is constant and you want to be able to predict the rate of cooling in the future you might be better off with plotting some observations on a chart and then using that as lookup, maybe against a given volume or starting temperature.
 
  • #4
@aiop: You need to do some thinking here, if you want a meaningful PF type conversation.
What mechanisms will be causing the heat loss? Which would be the major loss for hot water in a 'room temperature' room?
 
  • #5
Start by having a look at Newton's Law of Cooling...
 

What is the formula for calculating the time it takes for hot water to cool?

The formula for calculating the time it takes for hot water to cool is t = (Tf - Ti) / k, where t is the time in seconds, Tf is the final temperature in degrees Celsius, Ti is the initial temperature in degrees Celsius, and k is the cooling constant.

How do I determine the cooling constant for a specific container of hot water?

The cooling constant, k, can be determined experimentally by measuring the temperature of the water at regular intervals as it cools and plotting this data on a graph. The slope of the line on the graph will be equal to -k.

Can I use this formula to calculate the cooling time for any type of container?

Yes, this formula can be used to calculate the cooling time for any type of container as long as the cooling constant is known. However, the specific heat capacity of the container and any insulation it may have will affect the overall cooling time.

What is the most accurate way to measure the temperature of the hot water?

The most accurate way to measure the temperature of the hot water is by using a thermometer specifically designed for measuring liquid temperatures. Digital thermometers are often more accurate than traditional mercury thermometers.

How can I speed up the cooling process of hot water?

There are a few ways to speed up the cooling process of hot water, such as stirring the water or placing it in a colder environment. Adding ice cubes can also help to lower the overall temperature of the water more quickly.

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