PSLE
The graph shows the temperature of water in a pot from 1400 to 14 30.
- For how many minutes was the temperature of the water 80°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 1420 to 1425? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 14 10.
From 14 05 to 14 30: 25 min
Duration that the temperature of water that reached 80°C and below = 25 min
(b)
Decrease in temperature of water
From 14 00 to 14 05: 96°C - 80°C = 16°C
From 14 5 to 14 10: 80°C - 60°C = 20°C
From 14 10 to 14 15: 60°C - 41°C = 19°C
From 14 15 to 14 20: 41°C - 35°C = 6°C
From 14 20 to 14 25: 35°C - 18°C =
17°C
From 14 25 to 14 30: 18°C - 1°C =
17°C
Two 5-minute intervals that the temperature of water decreas
es at the same rate are 14 15 to 14 20 and 14 20 to 14 25. (c)
Change in temperature per minute from 14 20 to 14 25
= 17 ÷ 5
= 3.4°C/min
Answer(s): (a) 25 min; (b) 14 15 to 14 20, 14 20 to 14 25; (c) 3.4°C/min