Assuming a 300 ml cup with a diameter of 8 cm in a room at 24.6 °C, the time would be around 3 minutes and 43 seconds. To calculate the result:
Calculate the difference between the desired and the room temperature: 75 - 24.6 = 50.4 °C.
Calculate the difference between initial and room temperature: 90 - 24.6 = 65.4 °C.
Calculate the negative natural logarithm of the ratio of the previous results: -ln(50.4/65.4) = 0.26.
Divide the result by the constant k = 0.001165.
The result is 223 seconds, or just below 3 minutes, 43 seconds. Read more