### Fermi Problem Friday

How many times do your bicycle wheels spin around on your way to school?

Bonus question: Is this the same number of times your feet pedal around?

This might be difficult to answer if walk to school or take a train. In either case just cycle your feet around and pretend you are riding a bike. If people look at you funny, just tell them it's a physics project.

This excuse always works in any situation. For instance if you trip on the sidewalk and onlookers start laughing, just tell them you were testing Einstein's Theory of General Relativity. Suddenly they will be impressed.

1. My feet pedal around 1/3 the number of times as the wheel (fixed gear bike, 48 tooth front to 16 tooth rear), and with a roughly 27" diameter tire that's 7.06ft/turn, or 747.5 rotations per mile. I go ~10 miles, so ~7500 turns of the tire in that time, and ~2500 swings for each leg.

The rear inevitable spins slightly less than the front due to cornering too, which would be a very hard thing to calculate.

### How 4,000 Physicists Gave a Vegas Casino its Worst Week Ever

What happens when several thousand distinguished physicists, researchers, and students descend on the nation’s gambling capital for a conference? The answer is "a bad week for the casino"—but you'd never guess why.

### Ask a Physicist: Phone Flash Sharpie Shock!

Lexie and Xavier, from Orlando, FL want to know: "What's going on in this video ? Our science teacher claims that the pain comes from a small electrical shock, but we believe that this is due to the absorption of light. Please help us resolve this dispute!"

### The Science of Ice Cream: Part One

Even though it's been a warm couple of months already, it's officially summer. A delicious, science-filled way to beat the heat? Making homemade ice cream. (We've since updated this article to include the science behind vegan ice cream. To learn more about ice cream science, check out The Science of Ice Cream, Redux ) Image Credit: St0rmz via Flickr Over at Physics@Home there's an easy recipe for homemade ice cream. But what kind of milk should you use to make ice cream? And do you really need to chill the ice cream base before making it? Why do ice cream recipes always call for salt on ice?