//------------------------------// // Chapter 2 - Camera Trick // Story: Ponies Learn Calculus // by Lopsy //------------------------------// Twilight pranced around the field, giddy. “Eureka! Eureka!” “Um, English, Twi?” Rainbow Dash said. “I don’t speak Ancient Geek.” Twilight grabbed Rainbow’s shoulders, shoving her smile right into Dash’s face. “I’ve got it. This camera can tell us your exact speed, Rainbow Dash.” Pinkie Pie poked her head around it. “It can? I didn’t see a ‘Tell Me Rainbow Dash’s Speed’ button. Maybe you need a three-press combo…?” She started mashing buttons. “No, Pinkie.” Rainbow Dash rolled her eyes. “She means she can watch the trick again and again, and it’ll help her guess my speed better.” “Actually,” Twilight said, “it’s neither.” She took the camera back from Pinkie, and paused it at the critical moment of Rainbow’s trick. “The key is to watch the trick frame by frame.” “Wait, what?” Dash stared deep into the screen. Nothing happened. “…Sorry, Twi, I don’t think you can figure out my speed by watching me not move.” “Just watch.” Twilight pressed the frame advance button. On the screen, Rainbow Dash suddenly jumped forward. “Ooooooookay,” said Dash. “I’m watching.” “Now we can figure out how fast you’re moving.” Dash raised an eyebrow. “Bear with me. Pinkie, you said that this device records 30 images every second, right?” “Correctasaurus!” “Then, the time between this moment and this moment,” Twilight said, switching back and forth between the two frames, “is exactly 1/30 seconds.” “Oh. Ohh.” A lightbulb appeared over Rainbow Dash’s head. “Oooohhhhhhhhh! I got it!” Dash switched back and forth between the two frames. “What distance did I travel during those 1/30 seconds? Looks like… half a polylength? A little more?” Twilight pointed at the screen. Specifically, at the measuring stick on the ground. “If you compare your position relative to the measuring stick, it looks like you moved approximately 6/10 ponylengths.” (this is what you'd see if you switched back and forth between the two frames really fast) “Cool. We’ve got the distance, we’ve got the time. Now, the speed is, uh…” “Speed equals distance divided by time,” Twilight reminded her. “I’m not in first grade, Twi. I’ve got this. 6/10 ponylengths, divided by 1/30 seconds, is…” Pinkie jumped in front of her. “Ooooh! Ooooh! I know! It’s 87078952296/4837719572 ponylengths per second!” Dash stared at her. “Uh, what? Is that more or less than 20?” Twilight scribbled some numbers down on a piece of parchment. “It’s 18. Therefore, Rainbow Dash, you were traveling at approximately 18 ponylengths per second during the climax of your loop-the-loop.” Rainbow’s face slowly transformed into a grin. “YES! First-place trophy, here I come!” “Woo-hoo!” Pinkie Pie jumped on top of Dash, tackling her to the ground. “I’ll prepare the trophy-shaped cake. Twilight, aren’t you excited? On a scale from 10 to hot fudge, how excited are you?” Twilight was staring at the camera, transfixed. She examined it from every angle, furiously scribbling down notes. Twilight gazed back and forth between the camera and her equations. A little bit of drool came out of her mouth. “…Let’s just leave her be.” Rainbow said to Pinkie Pie. “She’ll be better in the morning.” Pinkie Pie didn’t respond. She was staring into space, mumbling. “What if the Canterlot mountains were made of rock candy? Ahhh…” Rainbow briefly wondered why so many of her friends occasionally went insane. But the thoughts of tomorrow’s competition soon overtook her. She flew up into the cool evening air, letting the orange sky surround her. She yawned. That rehearsal had taken a lot out of her. She had to wake up early tomorrow morning, too. She settled on top of a nearby cloud and plugged her ears with cloudstuff. On the other hoof… Rainbow unplugged her ears and took to the sky again. Slowly, she flipped herself upside-down. One more run through can’t hurt. After all, I have to be perfect.