PSLE
The graph shows the temperature of water in a pot from 1000 to 10 42.
- For how many minutes was the temperature of the water 70°C and below? Give your answer in min.
- During which two 7-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 1028 to 1035? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 10 14.
From 10 07 to 10 42: 35 min
Duration that the temperature of water that reached 70°C and below = 35 min
(b)
Decrease in temperature of water
From 10 00 to 10 07: 79°C - 70°C = 9°C
From 10 7 to 10 14: 70°C - 60°C = 10°C
From 10 14 to 10 21: 60°C - 45°C = 15°C
From 10 21 to 10 28: 45°C - 29°C = 16°C
From 10 28 to 10 35: 29°C - 22°C =
7°C
From 10 35 to 10 42: 22°C - 15°C =
7°C
Two 7-minute intervals that the temperature of water decreas
es at the same rate are 10 21 to 10 28 and 10 28 to 10 35. (c)
Change in temperature per minute from 10 28 to 10 35
= 7 ÷ 7
= 1°C/min
Answer(s): (a) 35 min; (b) 10 21 to 10 28, 10 28 to 10 35; (c) 1°C/min