How will your roly poly move?
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More about wheels
Some examples of different sorts of wheels are - plain discs, radial spokes and rim, tension spokes, pneumatic tyres.
The simplest wheel is a thin, solid, circular disc. When it is placed on its edge it is likely to overbalance. When it is given a push it rolls along, in a straight line keeping upright until it slows down or falls over.
Early wheels were like this. Wheels became lighter with the introduction of solid spokes. The wheel is made from an outer rim that is connected to a central hub by thin wooden spokes. This allowed wheels to become larger and lighter. They were used on large farm carts. You can see where the expression turning cartwheels comes from - the arms and legs look like the spokes in a cartwheel.
Early bicycles also had wheels like this. In later bicycles the spokes were made of very thin wire and held in tension. Each spoke could be individually adjusted so that the wheel could be made perfectly round and perfectly true.
Early tyres were made or iron. They were hard-wearing but very heavy. The introduction of the pneumatic tyre gave a much lighter wheel and the tread on the tyre provides extra grip.