A cup of coffee with temperature 155degreesF is placed in a freezer with temperature 0degreesF. After 5 ​minutes, the temperature of the coffee is 103degreesF. Use​ Newton's Law of Cooling to find the​ coffee's temperature after 15 minutes.

Respuesta :

Answer:

45.50° F

Step-by-step explanation:

As per Newton's law,

[tex]T(t) = T_{s}+(T_{0} + T_{s})e^{-kt}[/tex]

When T(t) is the final temperature

[tex]T_{s}[/tex] = Temperature of surrounding

[tex]T_{0}[/tex] = Initial temperature

t =duration of cooling

k = constant

[tex]103=0+(155-0)e^{-k\times 5}[/tex]

[tex]103=155e^{-5k}[/tex]

Now take natural log on both the sides

[tex]ln(103)=ln(155e^{-5k})[/tex]

[tex]ln(103)=ln(155)+ln(e^{-5k})[/tex]

[tex]ln(103)=ln(155)=-5k[/tex]

4.6347 - 5.0434 = -5k

[tex]k=\frac{0.40872}{5}[/tex]

k = 0.0817

[tex]T(t)=0+(155-0)e^{(0.0817\times 15)}[/tex]

   = [tex]155e^{-1.226}[/tex]

   = 155 (02935)

  = 45.49 ≈ 45.50° F