Newton's Law of Cooling (Calculating Time of Death)

[JacksonSolo]

Homework Statement

The problem states that you discovered the body at 1pm Thursday in a freezer where the temperature was 10F. Temperature of the corpse at discovery was 40F. I have to find how many hours ago the victim died.

Homework Equations

You are given the formula T = Ta + (98.6 - Ta)(0.97)^t where Ta is air temperature.

The Attempt at a Solution

So I plugged the numbers in: 40 = 10 + (98.6-10)(0.97)^t but I have no idea how to solve for t. Any help?

 

[sid9221]

Move the constants to one side and take logs on both sides you should get:

t log(0.97) = log \frac{30}{88.6}

Evaluate that for t.

 

[JacksonSolo]

Ok so I get the log of 30/88.6 and divide that by the log of 0.97 to get t, which equals 35.55 hours. Did I do that right?

 

[JacksonSolo]

Im just looking for confirmation i solved the problem right.

 

[DryRun]

It appears correct to me. But the answer is actually... 1:45 am on Wednesday?

 

[JacksonSolo]

Ok thanks. Yes, true ;)