Question

Suppose coffee is initially brewed at 205 F and the room temperature is 70 F. Determine the value of kk if the temperature of the coffee drops from 205 F to 200 F in the first two minutes after brewing. Round answer to 4 decimal places.

Answer 1

0.0189

Explanation:

We solve for this using Newton's Law of cooling.

The formula for Newton's Law of cooling =

T −Ts = (To−Ts)e^-kt

T = Temperature after cooling

To = Initial temperature

Ts = Room temperature

k = constant

t = time = 2 mins

(200 - 70) = (205 - 70)e^-2k

130 = 135e^-2t

e^-2k= 130/135

k = In(130/135)/-2

k = 0.018870164

Approximately to 4 decimal places = 0.0189

Therefore, the value of k = 0.0189