Steep mountain rivers flow at superhigh speeds. The water strips away bits of rock and carries them downhill.
After thousands of years, the river strips away enough rock to form a canyon. That’s a wide, deep crack in solid rock. If water can do that, imagine what else it can do. People put water to work long ago. They used it to move heavy objects. They used it to travel down rivers and across oceans. They even used it to keep time! Here are just a few of the water-powered machines and systems humans have built.
