Top-Speed Train Trick

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.

Top-Speed Train Trick

March 15, 2016

It would be so great if we humans could just stand up and fly away like birds do. We could get everywhere so much faster. But for now, we’re stuck riding cars, trains, boats or planes. So our friend Vasily M. asked, what’s the fastest you could get from New York to Los Angeles by train? (and drew this great picture to go along with it!) Well, that depends on the distance traveled, and the speed of the fastest train out there. There’s no train track that runs a perfect straight line from New York to LA. But if there were, it would be just 2,448 miles long, compared to 2,787 miles on the roads. Then we’d put the world’s fastest train on that track: The Shanghai Maglev line zooms at 268 miles per hour! On a straight coast-to-coast track, that train could reach California in just 9 hours 8 minutes. Luckily, a plane can fly it in about 5 1/2 hours, and that’s a lot less work.

Wee ones: If you take the 9-hour train trip and your friend takes a 5-hour flight, who takes less time to do the trip?

Little kids: If you take the super-speedy train to LA on the 2nd day of the month, then back to New York the 5th day, then back to LA the 8th day…when do you go back to New York to keep the pattern?  Bonus: On what day do you make your 6th train ride if you keep it up?

Big kids: If your track ends up 2 miles longer than the 2,448 miles you hoped for, how long is it?  Bonus: What’s the latest minute you could get on the train in LA time and make it to New York the same calendar day (11:59 pm), given that New York is 3 hours ahead?

The sky’s the limit: If you built a 300-mph train, then slowed it by 1/2 that speed, then slowed that new speed by 1/3, then slowed that new speed by 1/4, what fraction of your original speed is your train’s final speed?

 

 

 

Answers:
Wee ones: Your friend’s trip is shorter.

Little kids: On the 11th day, since it’s every 3 days.  Bonus: On the 17th day.

Big kids: 2,450 miles.  Bonus: 11:51 am. To get there by 11:59 pm New York time, you have to leave by 2:51 pm New York time, which is 3 hours earlier on the LA clocks.

The sky’s the limit: 1/4 of your original speed! You’d slow down to 150 (1/2 of 300), then to 100 (2/3 of 150), then to 75 (3/4 of 100). 75 is 1/4 of 300.

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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 while still in diapers, 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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