PJ Vogt

And it turns out that's contextual.

Don gave me an example.

So you're trying to figure out the right speed and angle for the car on one of those tight, curvy on-ramps onto the highway.

You want it to feel comfortable for a passenger.

Don says you can work out the math.

The lateral acceleration is two meters per second squared.

But the surprising thing is that number only applies on the on-ramp.

If I put you at a cul-de-sac in a neighborhood and you were going to do a U-turn at the end of the cul-de-sac, even though the speed is significantly slower, if you did two meters per second squared of lateral acceleration around a cul-de-sac, you would tell your driver they were crazy.

It would be incredibly uncomfortable.

Like, incredibly uncomfortable.

You would feel like you were in Mario Kart.

Yes, it would feel Mario Kart.

And remember, this is a force.

So it's a physical feeling on your body is exactly the same.

But the contextual awareness of the situation of speeding up to get on the highway versus making a U-turn in a residential street tricks your brain into feeling

opposite about the situation.

And so it turns out the limit for a cul-de-sac is around 0.75.

It's almost three times less than you would be willing to tolerate as you accelerate onto a highway.

And so there were things like that where you couldn't just say humans have specific physical restrictions.

From a forces perspective, the context matters.