PSLE
The graph shows the temperature of water in a pot from 1900 to 19 36.
- For how many minutes was the temperature of the water 60°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 1924 to 1930? Give your answer in °C/min.
(a)
Temperature of water that reached 55°C at 19 12.
From 19 06 to 19 36: 30 min
Duration that the temperature of water that reached 60°C and below = 30 min
(b)
Decrease in temperature of water
From 19 00 to 19 06: 79°C - 60°C = 19°C
From 19 6 to 19 12: 60°C - 55°C = 5°C
From 19 12 to 19 18: 55°C - 39°C = 16°C
From 19 18 to 19 24: 39°C - 32°C = 7°C
From 19 24 to 19 30: 32°C - 20°C =
12°C
From 19 30 to 19 36: 20°C - 8°C =
12°C
Two 6-minute intervals that the temperature of water decreas
es at the same rate are 19 18 to 19 24 and 19 24 to 19 30. (c)
Change in temperature per minute from 19 24 to 19 30
= 12 ÷ 6
= 2°C/min
Answer(s): (a) 30 min; (b) 19 18 to 19 24, 19 24 to 19 30; (c) 2°C/min