Unconvinced in Electric Brae

 Electric Brae is the famous place where cars roll uphill if you take the brakes off. I've been wanting to go for years. I confess to being a little disappointed. The slopes are so gentle that when we were there it was hard to figure. Funnily enough, I'm more convinced in hindsight by the photographs.

 In the picture above, the road is actually going downhill.

In the picture above, the road is sloping uphill. It does look downhill! Take the handbrake off and the car rolls backwards towards where I stood the picture. What's happening? I've been asked about it by classes many times in the past. I always make this model. The folded paper represents a river valley with a stream where the fold is. You know that the stream is at the bottom of the valley so you expect the road to be going DOWN to meet it. If you play with the angle of the V fold and the tilt of the paper, you can see that it is possible to have the road slope the wrong way.

 Above would be the Electric Brae set up. Below is what you mind expects.