The figure shows 2 containers, Container P and Container Q. Container Q is completely empty while Container P is filled with water to the brim. Water from Tap N flows in at a rate of 2.4 litres per minute while water drains from Tap M at a rate of 1.44 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 P
= 30 x 25
= 750 cm
2 1 ℓ = 1000 cm
3 2.4 ℓ = 2400 cm
3 1.44 ℓ = 1440 cm
3 Height increase per minute for Container P
= 2400 ÷ 750
= 3.2 cm/min
Base area of Container Q
= 40 x 20
= 800 cm
2 Height decrease per minute for Container Q
= 1440 ÷ 800
= 1.8 cm/min
Let t be the time taken for both the water levels to become the same.
3.2 t = 10 - 1.8 t
5 t = 10
1 t = 2 min
(b)
Height of the water level
= 3.2 t
= 3.2 x 2
= 6.4 cm
Answer(s): (a) 2 min; (b) 6.4 cm