The figure shows 2 containers, Container E and Container F. Container F is completely empty while Container E is filled with water to the brim. Water from Tap D flows in at a rate of 2.4 litres per minute while water drains from Tap C at a rate of 0.72 litres per minute. Both taps are turned on at the same time. After some time, the heights of the water level in both tanks became the same.
- Find the time taken for the heights of the water level to be the same in both tanks.
- Find the height of the water level at that point of time.
(a)
Base area of Container E
= 40 x 20
= 800 cm
2 1 ℓ = 1000 cm
3 2.4 ℓ = 2400 cm
3 0.72 ℓ = 720 cm
3 Height increase per minute for Container E
= 2400 ÷ 800
= 3 cm/min
Base area of Container F
= 20 x 18
= 360 cm
2 Height decrease per minute for Container F
= 720 ÷ 360
= 2 cm/min
Let t be the time taken for both the water levels to become the same.
3 t = 14 - 2 t
5 t = 14
1 t = 2.8 min
(b)
Height of the water level
= 3 t
= 3 x 2.8
= 8.4 cm
Answer(s): (a) 2.8 min; (b) 8.4 cm