The temperature of a liquid is decreasing at a constant rate. After two minutes of cooling, it was at 178 degrees and after five minutes of cooling it was at 154 degrees.

Question

What is the average rate of change for this scenario?

At what temperature did the liquid start cooling? Show how you arrived at your answer.

Answer 1

If the rate is constant, we can determine it from the second reading.

It went from 178 degrees to 154 degrees in 5 minutes. The rate is 178 - 164/5 = 24 degrees/5 min = 4.8 deg/min

Starting temperature can be deduced from this rate. Two minutes of cooling would be equal to 2 min x 4.8 degrees/min = 9.6 degrees. Initial starting temperature = 178 degrees + 9.6 degrees = 187.6 degrees.