PSLE
The graph shows the temperature of water in a pot from 1800 to 18 48.
- For how many minutes was the temperature of the water 50°C and below? Give your answer in min.
- During which two 8-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 1840 to 1848? Give your answer in °C/min.
(a)
Temperature of water that reached 50°C at 18 16.
From 18 16 to 18 48: 32 min
Duration that the temperature of water that reached 50°C and below = 32 min
(b)
Decrease in temperature of water
From 18 00 to 18 08: 78°C - 63°C = 15°C
From 18 8 to 18 16: 63°C - 50°C = 13°C
From 18 16 to 18 24: 50°C - 36°C = 14°C
From 18 24 to 18 32: 36°C - 26°C =
10°C
From 18 32 to 18 40: 26°C - 19°C = 7°C
From 18 40 to 18 48: 19°C - 9°C =
10°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 18 24 to 18 32 and 18 40 to 18 32. (c)
Change in temperature per minute from 18 40 to 18 48
= 2 ÷ 8
= 0.25°C/min
Answer(s): (a) 32 min; (b) 18 24 to 18 32, 18 24 to 18 32; (c) 0.25°C/min