Matt Morales
247 followers -
Foodie, techie and die-hard 49er fan
Foodie, techie and die-hard 49er fan

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We know you've heard this one before, but a bit more truth to the tale this go-round﻿
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This is a video of people rolling a bunch of tires off a ski jump, to see how far they'll fly. It's done with the combination of complete seriousness and excited insanity that defines Japanese television. And it does not disappoint.

For those of you interested in the physics, there are three main differences between the tires. The first has to do with what happens when a tire tries to roll down a hill: it picks up energy from descending, and that energy needs to be split between making the tire rotate (pulling all the mass of the tire in a circle around its center) and making the tire move forward. The more the mass is bunched towards the center of the tire, rather than its rim, the less energy it takes to make it rotate, and so the more energy is available for forward motion – and thus for being fired off the ski jump at speed.

The second has to do with how that rolling and moving are related. Obviously, the faster the tire is going forward, the faster it has to turn. In fact, if the tire is rolling without slipping, these two speeds are exactly related to each other. However, if the tire starts to slip, it can move forward without turning. Less friction means a tire has more speed for hurtling down the ski jump!

Of course, that's exactly the opposite of what you want when you attach a tire to a car, since a car moves because the engine turns the wheel, and you want that turning to convert directly into moving the car forward, not into making the tires spin. This is why high-performance tires (like the F1 tire in the video) are wide, entirely flat, and somewhat sticky: maximum friction. That's a terrible mixture for ordinary road tires, since if the road is even slightly wet, there's nowhere for the water to go except "lifting the tire directly off the road," aka "hydroplaning," aka "having a really bad day." Also, sticky tires wear out very fast, since they literally leave bits of themselves all over the road. Road tires instead have treads designed to channel things like water, snow, and debris out of the way.

As far as the third thing influencing the speed of the tires... well, you'll see what it is when they get to the last tire.

Via ﻿
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It's 🌸 season!

Don't miss a single Japanese cherry blossom with Street View: goo.gl/YwG5yR﻿
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That Refreshing Feeling
Snow Monkey, Japan.

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