hellllp plz (1 Viewer)

[Bl0nDi3]

cant do it trial 2molo seems like a 3u question its in my 2u book n 3u formula dsnt work

Newtons law of coolin states that the rate of coolin a body is proportional to the excess of its temp above its surroundings ie. dT/dt = -kt wer T(degrees) is the excess of temp above surroundings at any time t. The temp of a room is 25 and outdoor temp is 5. A thermometer which was in room is moved out doors. In 5 min it reads 15. Wat wud it read in another 5min

ans at back sez 10 degrees

 

[SoulSearcher]

I'll skip the finding of A, just know that A is 20 degrees
Temperature of thermometer:
T = 5 + 20e^-kt
When t = 5, T = 15
.'. 15 = 5 + 20e^-5k
10 = 20e^-5k
1/2 = e^-5k
-5k = ln (1/2)
k = ln(0.5)/-5
= 0.1386 ...
Find temperature when t = 10 minutes
T = 5 + 20e^-0.1386*10
= 5 + 5
= 10'C
Remeber to use exact values while doing the equation.

It is a 3 unit question, Newton's Law of Cooling is dealt in the 3 unit course.

 

[Bl0nDi3]

thxxxxxxx hahah yeh thats what i thought ...for some reason its in my 2u book

 

[SoulSearcher]

Which book is it? I've read the question before.

 

[Bl0nDi3]

Fitzpatrick 2u