PSLE
The graph shows the temperature of water in a pot from 1600 to 16 36.
- For how many minutes was the temperature of the water 70°C and below? Give your answer in min.
- During which two 6-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 1624 to 1630? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 16 12.
From 16 06 to 16 36: 30 min
Duration that the temperature of water that reached 70°C and below = 30 min
(b)
Decrease in temperature of water
From 16 00 to 16 06: 77°C - 70°C = 7°C
From 16 6 to 16 12: 70°C - 60°C = 10°C
From 16 12 to 16 18: 60°C - 54°C = 6°C
From 16 18 to 16 24: 54°C - 37°C = 17°C
From 16 24 to 16 30: 37°C - 28°C =
9°C
From 16 30 to 16 36: 28°C - 19°C =
9°C
Two 6-minute intervals that the temperature of water decreas
es at the same rate are 16 18 to 16 24 and 16 24 to 16 30. (c)
Change in temperature per minute from 16 24 to 16 30
= 9 ÷ 6
= 1.5°C/min
Answer(s): (a) 30 min; (b) 16 18 to 16 24, 16 24 to 16 30; (c) 1.5°C/min