Question

b) an experiment was set up using four identical styrofoam containers, e, f, g and h, with equal amounts of water. the temperatures of the water in the containers at the start of the experiment are shown in the diagram below. a glass rod and an iron rod were placed in the containers as shown. after five minutes, the temperatures of the water in the containers were measured. (i) arrange the containers according to the temperature of the water in them, from the lowest to the highest, by writing the letters e, f, g and h, in the correct boxes. lowest temperature → highest temperature 1 (ii) explain the difference in the temperatures of the water in containers f and h after five minutes. 1

Explanation:

(i)

Step1: Analyze thermal conductivity

Glass is a poor thermal conductor, iron is a good thermal conductor. For E (90°C, glass rod) and F (10°C, glass rod): little heat transfer. For G (90°C, iron rod) and H (10°C, iron rod): iron conducts heat, so G's heat transfers to H, and H's heat (less) to G? Wait, initial temps: E=90, F=10 (glass between them: low conductivity, so E stays ~90, F ~10? No, wait: E has 90, F has 10, glass rod connects them. Glass is insulator, so heat transfer between E and F is minimal. G has 90, H has 10, iron rod (conductor) connects them. So heat flows from G (90) to H (10) through iron, so G's temp drops, H's temp rises. So after 5 min: F (10, little change), E (90, little change), H (risen from 10), G (dropped from 90)? Wait no, wait: E and F: E is 90, F is 10, glass (insulator) – so E stays high, F stays low. G and H: G is 90, H is 10, iron (conductor) – heat flows from G to H, so G's temp decreases, H's temp increases. So final temps: F (10, maybe slightly up but little), E (90, slightly down but little), H (higher than 10, lower than 90), G (lower than 90, higher than H? Wait no, heat flows from hot to cold. So G (90) to H (10): H gains heat, G loses heat. So H's temp is between 10 and 90, G's temp is between 10 and 90, but G was 90, H was 10. So H's temp rises, G's temp falls. E and F: E was 90, F was 10, glass (insulator) – so E remains ~90, F remains ~10. So order from lowest to highest: F (lowest, ~10), H (next, risen from 10), G (next, fallen from 90), E (highest, ~90). Wait, no: wait E is 90, F is 10 (glass between, so E stays 90, F 10). G is 90, H is 10 (iron between: H gets heat from G, so H's temp is above 10, G's temp below 90. So F (10) < H (10 < H < 90) < G (90 > G > H) < E (90). Wait, no, E is 90, G was 90. After 5 min: E (glass, so 90 - small drop), G (iron, so 90 - bigger drop). F (glass, 10 + small rise), H (iron, 10 + bigger rise). So F < H < G < E? Wait, maybe. Let's think again:

• Container F: connected to E (90) via glass (poor conductor) – so F's temp remains ~10 (little heat transfer).
• Container H: connected to G (90) via iron (good conductor) – so H's temp rises from 10 (heat flows from G to H).
• Container G: connected to H (10) via iron – so G's temp falls from 90 (heat flows out to H).
• Container E: connected to F (10) via glass – so E's temp remains ~90 (little heat loss to F).

So final temps: F (lowest, ~10) < H (next, >10) < G (next, <90) < E (highest, ~90). So order: F, H, G, E.

Step2: Arrange containers

Based on thermal conductivity: glass (insulator) between E-F, iron (conductor) between G-H. So F (10, little change) < H (risen) < G (fallen) < E (90, little change).

Container F is connected to E via a glass rod (poor thermal conductor), so little heat transfers between E (90°C) and F (10°C). Container H is connected to G via an iron rod (good thermal conductor), so heat transfers from G (90°C) to H (10°C), increasing H’s temperature. Thus, H’s temperature is higher than F’s after five minutes because iron conducts heat better than glass, allowing more heat transfer to H.

Answer:

lowest temperature $\boldsymbol{F}$ $\boldsymbol{H}$ $\boldsymbol{G}$ $\boldsymbol{E}$ highest temperature

(ii)