How fast could YOU swim Burj Khalifa?

Getting my family moved back to the US from England and preparing for a new semester at Lynchburg College have greatly reduced the amount of time that I’ve had available for watching the Rio Olympics.  I certainly won’t be able to write blog posts at the rate I did during the 2012 Olympics in London (click here for a summary of what I wrote back then).  Despite how busy life for me is right now, I’ve been thrilled and moved watching the majesty of Simone Biles (born on Pi Day in 1997!) and the rest of the US women’s gymnastics team, the continued dominance of athletes like Usain Bolt and Michael Phelps, and the emotional win for Thiago Braz da Silva in the pole vault.  But one event really took my breath away, and that was the women’s 800-m freestyle.

Katie Ledecky (born on Saint Patrick’s Day in 1997, just three days after Simone Biles!) so dominated that event that I wondered if she would finish, hop out of the pool, and then enjoy a cool drink while watching the rest of the field finish.  She shattered the world record, setting the new standard for excellence at 8:04.79, which was more than 11 s quicker than silver medalist Jazmin Carlin of Great Britain.  Ledecky’s average speed was 1.65 m/s or 5.94 kph or 3.69 mph.  Consider that a typical walking speed is about 5 kph (3 mph), which means that Ledecky swam faster than someone walking over a distance of 0.8 km (0.5 mi).  I’m not in terrible shape, but swimming a half mile is a fairly daunting thought for me.  Doing so in anything close to eight minutes would be impossible for me!

How about more perspective on what Ledecky did?  The tallest building in the world is Dubai’s Burj Khalifa.  From ground to tip, the building stands 829.8 m (2722 ft) tall.  Elevators in that building are incredibly fast, with speeds of 10 m/s (36 kph or 22 mph).  That’s Usain Bolt speed, but Bolt can only sustain that average speed for 100 m or so.  I’m impressed that Bolt could keep up with Burj Khalifa’s elevators for about 20 floors.  But I’m equally impressed that Ledecky could swim the entire length of Burj Khalifa in about 8.5 minutes.  Thinking “outside the pool” sometimes helps me gain better perspective.

I am Professor of Physics at Lynchburg College and author of Gold Medal Physics: The Science of Sports.

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