contestada

At 3 p.m., a hot coal was pulled out of a furnace and allowed to cool at room temperature (75°F). If, after 10 minutes, the temperature of the coal was 475°F, and after 20 minutes, its temperature was 395°F, find the following.

(a) The temperature of the furnace.
°F

(b) The time when the temperature of the coal was 105°F. (Round your answer to the nearest minute.)
: p.m.

Respuesta :

MissPhiladelphia
a. This can be solved using Newton's Law of Cooling
T - To = (Tb - To)e^kt
From the given conditions
T = 475 F
To = 75 F
t = 10 min
475 - 75 = (Tb - 75)e^k(10)

For the second condition
T = 395 F
To = 75 F
t = 20 min
(395 - 75) = (Tb - 75)e^k(20)

There are two unknowns and two equations, solve for
k and Tb

You can then use this to solve for the time until the T = 105 F

Otras preguntas