3 ms·
Why would the wheel rims rotate at twice the speed of the train? If the train advanced along the track 1m, surely the part of the wheel in contact with the trac
by littlejohnk 11y ago
Why would the wheel rims rotate at twice the speed of the train? If the train advanced along the track 1m, surely the part of the wheel in contact with the track must also have moved 1m?
- Retric 11y agoThe bottom of a wheel is stationary relative to the ground. (X - X) The middle a the wheel moves at the same speed as the vehicle relative to the ground. (X + 0) The top of the wheel moves at twice the speed of the vechile relative to the ground. (X + X) Put another way, the top of the wheel must go faster than the vehicle or it does not rotate.
- HCIdivision17 11y agoI think the idea is that the top of the wheel is basically super sonic compared to the ground. This has to be the case: the train is connected to the middle of the wheel at speed, the bottom of the wheel is going 0 so long as it's not slipping, so the top of the wheel is screaming along at near-sonic speeds. It's an odd diagram to draw out, as that result is pretty counter-intuitive.