A cup of tea is served at 90 °C in a room whose temperature remains fixed at 30 °C
PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A cup of tea is served at 90 °C in a room whose temperature remains fixed at 30 °C. The constant k governing the rate of cooling is 0.05 min−1.
(i) Find the temperature of the tea after 20 minutes, correct to the nearest degree.
(ii) How long, from the moment it was served, will it take for the tea to cool to a comfortable drinking temperature of 45 °C? (Give your answer correct to one decimal place.)