Really weird hubcaps...
Driving around Waltham last week I saw a really weird car.
Starting from a full stop, the wheels started turning, but the hubcaps had inertia, and didn't start turning until the car was up to speed. The net-effect is that the caps appear to be spinning. Very interesting effect.
My dad would love these things, and his birthday is on Friday. (And Father's Day is Sunday.)
Does anyone know how they work, and where I can buy a set of them?