Certain animals living in cold environments must limit how much heat escapes from their bodies.
A student explored how an insulating material affects heat loss from an animal. A test-tube was used to model the animal, and wool, which is known to be a good insulator, was used.
A line was marked on the test-tube 2 cm below the top.
The wool was put into a beaker, and the test-tube was inserted so that it was fully surrounded by wool, as shown in Fig. 1.1.
A second marked test-tube was set in a test-tube rack, as shown in Fig. 1.1. No insulation was used for this one.
Hot water was poured into both test-tubes up to the marked lines.
The timer was started immediately, and the temperature of the water in each test-tube was measured.
(a)[1]
Suggest why both test-tubes were filled with water only up to the marked line.
(b(i))[4]
Transfer every temperature reading into Table 1.1.
(b(ii))[3]
Use the results in Table 1.1 to describe how heat is lost from the test-tubes and how the insulation affects this.
(c)[6]
Humpback whales are large aquatic mammals with a constant body temperature of $38\,^\circ\text{C}$. For part of the year they live in cold polar water, and for part of the year they live in warm equatorial water.
Design an investigation that you could carry out to find out how different surrounding water temperatures affect the loss of heat by the humpback whale. Use a test-tube containing water to model the humpback whale.
Worked solution & mark scheme
This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Use the same volume of water in each test-tube so that the water does not spill over when the thermometer is inserted / while the temperature is being measured” …