Mochi Isle
Waterwheel · Bamboo ValleyScience for kidsHow does flowing water turn a waterwheel?
In short: Flowing water pushes on a waterwheel's paddles or buckets and makes it spin. The axle in the middle turns with it, and through gears it can drive a millstone, a pump or a saw to do useful work.
How it works
Moving water carries energy, so just as wind turns a windmill, water can turn a wheel. In some waterwheels the bottom sits in the river and the current rushes past the paddles. In others, water pours into buckets at the top, and the weight of the water pulls that side down.
A strong axle runs through the centre, so when the wheel turns, the axle turns too. Gears on the axle can change the direction and speed of turning, for example turning an upright wheel into a flat millstone to grind flour. Waterwheels have also pounded grain and lifted water onto fields.
Today's hydro power stations use a modern cousin of the waterwheel called a turbine. Water from high up rushes through a pipe, spins the turbine very fast, and the turbine drives a generator that makes electricity. It is the same idea, just bigger and more efficient.
Where to see it in New Zealand
A large share of New Zealand's electricity comes from hydro power. The Waikato River in the North Island has a whole chain of hydro stations, and in the South Island the Clyde Dam sits on the Clutha River. Water spins giant turbines, like supersized waterwheels, turning moving water into electricity for homes.
Try it together
At a sink or with a garden hose, hold a plastic toy pinwheel under a gentle stream of water and watch it spin. Try aiming the water at different parts of the blades, and make the flow stronger or weaker.
Kids also ask
How is a waterwheel different from a windmill?
They work the same way: something flowing pushes blades around. A windmill uses moving air and a waterwheel uses moving water. Water is far heavier than air, so it can push much harder.
Can still water turn a waterwheel?
No. Still water does not push anything. A waterwheel needs water flowing down or along. The faster the flow, or the further the water falls, the more force it can give.
What were waterwheels used for?
They ground grain into flour, pounded rice, lifted river water onto fields, sawed timber and worked heavy hammers for blacksmiths. Before electricity, they were one of the most important sources of power.
In the game, “Waterwheel” is a nature card on Bamboo Valley.
Your child finds this card by reaching the right place or meeting the right weather on the island, and lights it up by answering the question on the back. Tap the button below and the game shows your child which island it is on and how to find it. Mochi Isle is a browser learning game for ages 5 to 18; the main island and the daily lesson are free.
Find “Waterwheel” on the island ↗ All cards from Bamboo Valley