- 3 You Are Attending A Conference And The Talks Are Going Past The Coffee Break Time You Really Need A Cup Of Tea Not 1 (128.54 KiB) Viewed 19 times
This is all one problem.
3. You are attending a conference, and the talks are going past the coffee break time. You really need a cup of tea (not liking coffee) to keep awake for the next set of talks. The refreshments are in a room that has a constant temperature of 21°C, and you find that the hot water is only 85°C. Five minutes later, the hot water is only 81°C. a. Assume that the container of water satisfies Newton's law of cooling. (H' = -k(H – Te), where Te is the environmental temperature.) If it was placed out when the talks were supposed to end = = with boiling water (water at 100°C), then how many minutes beyond the scheduled time did the talks go? (Hint: If H(t) is the temperature, then use H(0) = 85 and H(5) = 81 to find the cooling constant k in Newton's law of cooling, then find when H(t) = 100.) b. If tea needs water that is at least 93°C to give you enough caffeine for the next set of talks, then how long after the scheduled end of the talks can you wait?