PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
A loaf of bread is taken out of an oven. At t=0, its core temperature is 98 °C. The bakery kitchen is kept at 75 °F. Ten minutes later, the bread’s core temperature is measured to be 70 °C.
(i) Convert the ambient temperature to degrees Celsius, correct to one decimal place.
(ii) Form the differential equation satisfied by the temperature θ(t) of the bread (in °C) at time t minutes, and solve it to obtain θ(t) in terms of an unknown constant k.
(iii) Determine the value of k using the data provided.
(iv) Using the value of k found in part (iii), calculate the bread’s temperature after a further 15 minutes.
(v) After how many minutes from t=0 will the bread’s core temperature reach 40 °C? (Give your answer correct to two decimal places.)