PSLE
The graph shows the temperature of water in a pot from 1100 to 11 30.
- For how many minutes was the temperature of the water 60°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 1120 to 1125? Give your answer in °C/min.
(a)
Temperature of water that reached 50°C at 11 10.
From 11 05 to 11 30: 25 min
Duration that the temperature of water that reached 60°C and below = 25 min
(b)
Decrease in temperature of water
From 11 00 to 11 05: 79°C - 60°C = 19°C
From 11 5 to 11 10: 60°C - 50°C = 10°C
From 11 10 to 11 15: 50°C - 35°C = 15°C
From 11 15 to 11 20: 35°C - 21°C = 14°C
From 11 20 to 11 25: 21°C - 16°C =
5°C
From 11 25 to 11 30: 16°C - 11°C =
5°C
Two 5-minute intervals that the temperature of water decreas
es at the same rate are 11 15 to 11 20 and 11 20 to 11 25. (c)
Change in temperature per minute from 11 20 to 11 25
= 5 ÷ 5
= 1°C/min
Answer(s): (a) 25 min; (b) 11 15 to 11 20, 11 20 to 11 25; (c) 1°C/min