The figure shows 2 containers, Container W and Container X. Container X is completely empty while Container W is filled with water to the brim. Water from Tap V flows in at a rate of 1.2 litres per minute while water drains from Tap U at a rate of 2.16 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 W
= 40 x 15
= 600 cm
2 1 ℓ = 1000 cm
3 1.2 ℓ = 1200 cm
3 2.16 ℓ = 2160 cm
3 Height increase per minute for Container W
= 1200 ÷ 600
= 2 cm/min
Base area of Container X
= 20 x 18
= 360 cm
2 Height decrease per minute for Container X
= 2160 ÷ 360
= 6 cm/min
Let t be the time taken for both the water levels to become the same.
2 t = 14 - 6 t
8 t = 14
1 t = 1.75 min
(b)
Height of the water level
= 2 t
= 2 x 1.75
= 3.5 cm
Answer(s): (a) 1.75 min; (b) 3.5 cm