A thermometer is taken from an inside room to the

eliaskidszs

eliaskidszs

Answered question

2021-12-26

A thermometer is taken from an inside room to the outside ,where the air temperature is 5F. After 1 minute the thermometer reads 55F, and after 5 minutes it reads 30F, what is the initial temperature of the inside room?

Answer & Explanation

Juan Spiller

Juan Spiller

Beginner2021-12-27Added 38 answers

Let the temperature of the thermometer at any time t is given by: y(t)
The temperature of the surrounding is: A
dydt=k(yA); where k is the constant of proportionality
A=5
dydt=k(y5)
Solving this differential equation we get:
y(t)=5+Cekt
Now, after 1 minutes thermometer reads: 55F
y(1)=55
5+Cek=55
Cek=50 (1)
Now after 5 minutes thermometer reads: 30F
y(5)=30
5+Ce5k=30
Cek=25 (2)
Now solving equation (1) and (2):
C=59.4611 and k=0.1733
Therefore: y(t)=5+59.4611e0.1733t
Hence the initial temperature is:
y(0)=64.4611F
Samantha Brown

Samantha Brown

Beginner2021-12-28Added 35 answers

The DE for Newtons
karton

karton

Expert2022-01-09Added 613 answers

dydt=k(yA);A=5dydt=k(y5)y(t)=5+Cekt55Fy(1)=555+Cek=55Cek=50(1)30Fy(5)=305+Ce5k=30Cek=25(2)C=59.4611 and k=0.1733y(t)=5+59.4611e0.1733ty(0)=64.4611F

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