Newton's law of cooling question, no inital temperature given

[miniradman]

Homework Statement

The temperature of an object has been lying at rest and cooling for sometime had been found to be 31^oC. An hour later, the same object was found to be 30^oC. The room was also What was the initial temperature of the object, assume Newton's law of cooling applies.

Homework Equations

Newton's law of cooling

[itex]\frac{dT}{dt}[/itex] = k (T - T_s) where:

T_s = ambient temperature
T = the temperature at anytime
k = constant of proportionality

The Attempt at a Solution

Ok, normally when I do a Newtons law of cooling question, I start off with the inital temperature followed by a temperature at an "X" time. And then I would convert the formula into it's exponential form i.e. y = Ae^kt+c. then I would use the initial temperature (or the temperature when t=) to cancel out one of the variables. However, I'm trying to find the inital temperature, so this method won't work for me anylonger and I'm not sure how to proceede

Thanks guys/gals, any help will be greatly appreciated

 

[Mark44]

Homework Statement

The temperature of an object has been lying at rest and cooling for sometime had been found to be 31^oC. An hour later, the same object was found to be 30^oC. The room was also What was the initial temperature of the object, assume Newton's law of cooling applies.

"The room was also" - what? Where's the rest of this sentence?

Homework Equations

Newton's law of cooling

[itex]\frac{dT}{dt}[/itex] = k (T - T_s) where:

T_s = ambient temperature
T = the temperature at anytime
k = constant of proportionality

The Attempt at a Solution

Ok, normally when I do a Newtons law of cooling question, I start off with the inital temperature followed by a temperature at an "X" time. And then I would convert the formula into it's exponential form i.e. y = Ae^kt+c. then I would use the initial temperature (or the temperature when t=) to cancel out one of the variables. However, I'm trying to find the inital temperature, so this method won't work for me anylonger and I'm not sure how to proceede

Thanks guys/gals, any help will be greatly appreciated

 

[miniradman]

Sorry, the room was also found to be 20 degrees celsius

 

[Bohrok]

Take the initial temperature to be 31°C at t=0. The time spent lying at rest in the room doesn't matter before the temp was measured.