How Long Until a Hot Metal Rod Cools to 150F in a Water Bath?

In summary, we are given a hot metal rod placed in a water bath with a temperature of 40F. The rod cools from 300F to 200F in 1 minute. Using the equations y'=-k(y-T0) and y(t) = T0 + Ce^-kt, we can solve for the parameters T0, C, and k. T0 represents the initial temperature of the rod, at which the temperature is 300 degrees F. The temperature of the rod reaches 200 degrees F after 1 minute, and these values can be used to solve for C and k. Using the formula for temperature, we can then find the time at which the rod will cool to 150 degrees F.
  • #1
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Homework Statement


A hot metal rod is placed in a water bath whose temperature is 40F. The rod cools from 300F to 200F in 1 minute. How long will it take for the rod to cool to 150F?


Homework Equations





The Attempt at a Solution


I know y'=-k(y-T0)
and y(t) = T0 + Ce^-kt
and i also know that's not much of a start...
 
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  • #2
What you show as your attempt are actually the relevant equations. The first is the differential equation that relates the rate of cooling (y'(t)) to the temperature y(t). The second equation is the general solution to the differential equation.

How the solution is gotten from the differential equation might be more advanced than you can understand right now, so what you need to do is use the given information about the temperatures at the two times to find the parameters T0, C, and k. Then you will be able to use the formula to calculate the temperature at any time t.

Some questions for you:
What does T0 represent?
At what time is the rod's temperature 300 degrees F?
At what time is the rod's temperature 200 degrees F?

Use the formula for temperature to write equations involving the information above and solve for C and k, then use your formula to find the time at which the rod has cooled to 150 deg. F.
 

FAQ: How Long Until a Hot Metal Rod Cools to 150F in a Water Bath?

What is Newton's law of cooling?

Newton's law of cooling is a physical law that describes the rate at which an object cools down when placed in a different temperature environment.

How does Newton's law of cooling work?

The law states that the rate of cooling of an object is directly proportional to the temperature difference between the object and its surroundings. This means that the larger the temperature difference, the faster the object will cool down.

What is the formula for Newton's law of cooling?

The formula for Newton's law of cooling is T(t) = Ts + (T0 - Ts)e-kt, where T(t) is the temperature of the object at time t, Ts is the temperature of the surroundings, T0 is the initial temperature of the object, and k is a constant determined by the properties of the object and its surroundings.

What are the limitations of Newton's law of cooling?

Newton's law of cooling assumes that the temperature difference between the object and its surroundings is constant, the object is in a well-mixed environment, and there is no heat generated or lost by the object. These assumptions may not hold true in real-world situations, leading to deviations from the predicted cooling rate.

How is Newton's law of cooling applicable in everyday life?

Newton's law of cooling can be applied in various everyday situations, such as cooking, heating and cooling systems, and refrigeration. It is also used in fields like meteorology and food preservation to understand and predict temperature changes. Additionally, it has practical applications in industries like engineering and materials science.

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