Why We Run in the Rain

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

Why We Run in the Rain

October 23, 2017

Do we even want to run in the rain? Usually no. But if it’s raining outside and you just have to get from here to there, here’s the question: will you get wetter running or walking? On the one hand, some number of drops will land on your head each minute. If you just stand there, your head will get wet. But as you move forward, the front of you gets wet, because there are always raindrops hanging in the air on their way down, and you run into them. So what should you do? It looks like running may be better: Assuming no wind, the front of you will catch the same number of drops as you move through the air, whether you run fast or slow. But the longer you take, the longer your head is catching drops. So you might as well hurry up. And if you’re really smart, maybe you should just open an umbrella.

Wee ones: Who’s wetter, you with 10 raindrops on your head, or your pet poodle with 8 raindrops on his?

Little kids: If you run 2 steps in the rain, then walk 3 steps, then run 4 steps…what do you guess you do next?  Bonus: How many wet steps did you take in total?

Big kids: If each foot-deep chunk of air in front of you has 50 falling raindrops, how many drops do you soak up if you walk 10 feet?  Bonus: Which way will you get wetter, catching 25 drops per second while you run for 4 seconds, or catching 15 per second walking for 8 seconds?




Wee ones: You’re wetter with 10 raindrops.

Little kids: Walk 5 steps to continue the pattern.  Bonus: 14 steps.

Big kids: 500 drops.  Bonus: You’ll get wetter walking, with 120 raindrops instead of 100.

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About the Author

Laura Overdeck

Laura Overdeck

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.

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