Did a Rock Hit Your Windshield, or Did Your Windshield Hit a Rock?
You’re driving along, minding your own business, and—TING! Something smacks your windshield. You didn't see it coming, but the glass is cracked. Where the heck did it come from, and why did it hit your windshield? As I always say, you don’t understand something unless you can model it. So let’s try a little thought experiment. We’ll start with a basic scenario, where someone ahead of you drops an object in the road, and then see what we need to make it work. Follow the Bouncing Ball OK, imagi