A student wants to find out which of the three materials is the best thermal insulator. The student’s apparatus at the beginning of each test is as shown in the figure below.
Each beaker is surrounded by a different insulating material. The water is allowed to cool and the temperatures are recorded at different times. The student is unable to write a correct conclusion because the variables have not been controlled.
(a) Study the figure and then state two ways in which you would improve the control of variables.
(b) State the reading shown on the thermometer below.
What is temperature reading ?
(c) The graph below shows the results obtained by the student.
The graph lines A, B and C correspond to the beakers A, B and C.
Which beaker cools the most quickly in the first 60 s?