Pouring Water Between Two Containers
Primary 5 pouring between containers questions: the liquid keeps its volume, so add, subtract and compare capacities in ml and cm³.
Questions in this lesson
Transcript
Tank A has a length of 30 cm and a breadth of 20 cm. The water in it is 18 cm high. All of the water is poured into Tank B, which is empty. Tank B has a length of 40 cm and a breadth of 30 cm. Find the height of the water in Tank B. Pouring changes the tank, but not the amount of water. So first find the volume of the water. Volume is length times breadth times height. 30 times 20 times 18 is ten thousand, eight hundred cubic centimetres. Now pour all of it into Tank B. The base of B is bigger, so the same water stands lower. The base area of B is 40 times 30. That is one thousand, two hundred square centimetres. Divide the volume by the base area. Ten thousand, eight hundred divided by one thousand, two hundred is 9. So the height of the water in Tank B is 9 centimetres.
Your turn. A jug holds 3 litres of water. All of it is poured into an empty tank with a length of 20 cm and a breadth of 15 cm. Find the height of the water in the tank. Try it first. Pause if you like. 3 litres is three thousand millilitres. Every millilitre is one cubic centimetre, so the water is three thousand cubic centimetres. Pour it into the tank. The base area is 20 times 15, which is three hundred square centimetres. Three thousand divided by three hundred is 10. So the height of the water in the tank is 10 centimetres. Poured water keeps its volume, not its height. To find its new height, divide the volume by the new base area.