PSLE
The graph shows the temperature of water in a pot from 1000 to 10 30.
- For how many minutes was the temperature of the water 55°C and below? Give your answer in min.
- During which two 5-minute intervals did the temperature of water decrease at the same rate? Give your answer in the following format. (Eg 01 00 to 01 15, 01 25 to 01 30)
- What was the change in temperature per minute from 1025 to 1030? Give your answer in °C/min.
(a)
Temperature of water that reached 55°C at 10 10.
From 10 10 to 10 30: 20 min
Duration that the temperature of water that reached 55°C and below = 20 min
(b)
Decrease in temperature of water
From 10 00 to 10 05: 81°C - 71°C = 10°C
From 10 5 to 10 10: 71°C - 55°C = 16°C
From 10 10 to 10 15: 55°C - 47°C = 8°C
From 10 15 to 10 20: 47°C - 40°C =
7°C
From 10 20 to 10 25: 40°C - 25°C = 15°C
From 10 25 to 10 30: 25°C - 18°C =
7°C
Two 5-minute intervals that the temperature of water decreas
es at the same rate are 10 15 to 10 20 and 10 25 to 10 20. (c)
Change in temperature per minute from 10 25 to 10 30
= 1 ÷ 5
= 0.2°C/min
Answer(s): (a) 20 min; (b) 10 15 to 10 20, 10 15 to 10 20; (c) 0.2°C/min