Book 3, Question 4
Why Do Wheels Beat Dragging?
A wheel touches the ground with only a tiny patch. Dragging is a long scrape, but rolling is a tiny touch. That means much less rubbing, so your load moves with a lot less effort!
From the book
Page from A Million Whys Book 3
More fun facts
- The first wheels were probably potter's wheels, used in Mesopotamia around 3500 B.C.
- Wheels were used for pottery about 300 years before people put them on chariots.
- Wheelbarrows were expensive in the past, but they could pay for themselves in just 3 or 4 days of saved work.
- Archaeologists in Vera Cruz, Mexico, found ancient clay toy animals that rolled on wheels instead of legs.
- The first United States patent involving a wheel was issued on August 26, 1791.
- The first Ferris wheel, shown in Chicago in 1893, was 250 feet across and could carry 2,160 people per trip.
- When one wheel on NASA's Spirit rover on Mars developed more friction than the others, the rover drove backward dragging that wheel, which left a scraped track in the soil.
Sources: Smithsonian Magazine, NASA Science
Questions kids ask
Who invented the wheel?
No one knows the inventor's name, but evidence shows wheels were used as potter's wheels in Mesopotamia around 3500 B.C., before they were put on carts and chariots.