Posts from: January '15
I've recently taken upon using the public transit again, since I no longer have a car. Whenever taking a bus or the metro, I try to position myself in a way that will save me time later (to be near an exit or a tunnel or whatever I'm expecting at my destination). This just moves some future walking to take place now, but I don't need to value my time while still waiting for the transportation. Yes, seems like a minuscule optimization - but wait, there's more!
In some cases, when I caught the bus in the last second, I might have gotten on the back side, whereas the optimum would be to reposition in front. There are three choices on when to reposition, provided that the bus is empty enough:
- while the bus is moving at a constant speed;
- while the bus is accelerating (which forces you back, impeding your movement)
- while the bus is decelerating (which makes it easier).
Being bored, one day I pondered on which of the three is optimal. By the Law Of Universal Misery And Suffering I suspected it to be #2, but it is indeed the last one. When you're moving forward in a decelerating vehicle, you're reducing the mass that needs to be stopped, so less braking force is required and the brakes last the tiniest bit longer. Similarly, when you're moving back in an accelerating vehicle, the engine doesn't need to push the whole bus and you, so a minuscule quantity of fuel is saved.
In summary, this is one of the rare occasions where the physics laws cancel out in your favor. The profit is almost nothing, of course, but it cheered me up :)