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Dash
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dash Paper Folding Limit
When you fold paper, / each time it gets thick! / Seven folds are tough, / the math does the trick!
dash Proportional Theory of Time
Time goes fast, time goes fast 'Cause each year is smaller than the last!
dash Drag the shrinking timeline to learn the math of why time feels faster every year.
dash Exciting trips feel short while happening but seem long in retrospect because of rich memory storage.
Fun Fact
Life milestones: At age seven, a single summer vacation of two months represents roughly 2.4% of your entire life, whereas at age fifty, it is a tiny 0.3%.
dash Our brains process sensory inputs and time on a multiplying logarithmic scale rather than a linear one.
Glossary
proportional theory (noun)
A psychological concept proposing that the subjective speed of time is relative to one's total lifespan. French philosopher Paul Janet proposed this idea in 1877 to explain the psychological acceleration of aging.
A psychological concept proposing that the subjective speed of time is relative to one's total lifespan. French philosopher Paul Janet proposed this idea in 1877 to explain the psychological acceleration of aging.
Quiz
If subjective time is inversely proportional to age, how does a year feel to an older person?
Gossip
Would you slow down your perception of time if it made chores feel longer?
Quiz
In what century did scientists first publish mathematical models explaining why time seems to speed up?
Quiz
What mathematical term describes a scale where values increase by multiplication, matching how humans perceive time?
Quiz
What percentage of a five-year-old's life does a single year represent?
Quiz
According to mathematical models of subjective time, by what age have you experienced about half of your subjective life?
Quiz
What fraction of a fifty-year-old's life does a single year represent?
Quiz
Which famous psychologist described the holiday paradox where busy times feel short but look long in retrospect?
Quiz
Which philosopher proposed the proportional theory of time in 1897?
dash Drag and tie different shoelace patterns to discover the surprising math behind secure knots.
dash Shoelace Knot Physics
Stomp loosens the loop—(drop it low!) / Swing whips the ends loose—(there they go!)
dash Alternating directions creates a flat, self-tightening square knot.
Fun Fact
Shoelace tips: The plastic or metal tip at the end of a shoelace is called an aglet, which prevents fraying.
dash Matching the starting knot and bow directions creates a weak, twisting knot.
Glossary
granny knot (noun)
An insecure knot made by crossing the ends of a cord twice in the same direction. In 2005, Terry Moore demonstrated at TED how this unbalanced structure causes shoelaces to constantly untie.
An insecure knot made by crossing the ends of a cord twice in the same direction. In 2005, Terry Moore demonstrated at TED how this unbalanced structure causes shoelaces to constantly untie.
Quiz
What physical force keeps a tied shoelace knot from immediately falling apart?
Quiz
Which basic starting knot direction sequence produces a strong reef knot?
Quiz
What happens to a reef knot when you pull the two outer ends of the shoelaces?
dash Time each foot strike to discover how sprinters use physics to run incredibly fast.
Quiz
What is the primary difference between a weak granny knot and a strong reef knot on a shoelace?
Quiz
What mathematical property describes a knot that cannot be untied without cutting the loop?
Quiz
Which knot-tying method, invented by Ian Fieggen in 1982, is known as the fastest way to tie a secure shoelace?
Quiz
In what year did Ian Fieggen introduce his famous ultra-fast shoelace-tying technique?
dash Physics of the Foot Strike
Strike the track hard! (Yeah, slam it down!) Fly in a flash! (Oh, hit and bounce!)
dash Speed is a simple mathematical equation multiplying how far you step by how fast you step.
Fun Fact
Achilles spring power: A kangaroo’s hopping efficiency is highly dependent on elastic tendons, a mechanism human sprinters mimic to bounce off the track.
dash The fastest runners spend less time touching the ground, allowing them to maintain high speeds.
Quiz
Which mathematical formula determines a runner's overall speed?
Quiz
What is the average ground contact time for an elite sprinter's foot strike?
Quiz
At what angle should a sprinter bend their elbows to optimize arm drive?
Quiz
How many strides did Usain Bolt take to complete his 9.58-second 100-meter world record run?
Quiz
Which tendon acts as the primary natural spring in a sprinter's leg?
Quiz
What is the primary role of a sprinter's arms during a high-speed race?
Quiz
Why do elite sprinters focus heavily on minimizing their ground contact time?
Quiz
How much force does Usain Bolt's foot exert on the track during a sprint?