This Spring Break, the Science Mill is exploring the science behind your favorite sports with two-weeks of heart-pumping activities. Start training with this intro to the six simple machines that help our bodies, inside and out.

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Two unlikely things that have a lot in common: the Olympics and the Science Mill’s Incredible Ball Machine. Sure, both are filled with thrills and spills. But behind the complex action, what they really share are simple machines.

Simple machines use energy to perform work. By harnessing the energy of motion, they make our work easier—like helping us move heavy loads or get somewhere faster with less effort.

In the Incredible Ball Machine, you’ll spot gears (wheel and axle), pulleys, slanted tracks (inclined planes), an auger (screw) and even a skateboard lever working together to keep balls in motion. (The only simple machine you won’t spot is a wedge.)

And at the Olympics? Winter or summer, you’ll see athletes team up with simple machines. Divers bouncing on boards, crews rowing with oars, and hockey players swinging sticks all put different types of levers to work. Some simple machines are obvious, like the wheels and axles that propel bike races; others are more hidden, like the pulleys used to control rigs in sailing competitions. And those snow-covered slopes that make for extreme skiing are really massive inclined planes!

The coolest simple machines, however, are inside the athletes’ bodies—and yours. Our bones, joints and muscles act as levers, with elbows and the balls of our feet as fulcrums. Ball-and-socket joints in our shoulders and hips aren’t true wheels and axles, but serve a similar function. (Wheels don’t really occur in living things; there’s an evolutionary dilemma of how to get nutrients to a free-moving part. But scientists have discovered a weevil with screw-and-nut knee joints!) Our tendons and kneecap form a pulley system that redirects force, keeping our bones from crunching together as we lift and bend the lower leg. Our teeth are an all-star team of tiny wedges.

As complex machines, our bodies do an amazing job of coordinating these simple machines with other systems; yet sometimes things go wrong. Misdirected forces may make work less efficient or cause strain and injury. Reminders to “lift with the legs” or “stand up straight” are actually ways to keep our body machines in balance. Understanding the simple machines at work in our bodies is important not only to athletes and trainers, but to many STEM careers, including surgeons, physical therapists, rehabilitation specialists, designers of orthotics and prosthetics, ergonomic analysts, biomedical engineers, and roboticists.

TRY IT AT HOME OR SCHOOL

Compete in the Simple Machines Olympics!
Check out our Explorer Zone video on the Incredible Ball Machine for info and inspiration, then choose how you want to compete:

• Design challenge – Come up with a Rube Goldberg-inspired contraption that uses multiple simple machines to complete a task in a wild way. Earn a perfect technical score (6/6) by incorporating an example from each of the six classes of simple machines; increase your style score with one point for every simple machine you use in total.

• Physical challenge – Create a hexathlon (aka a six-event competition) with an event for each of the six simple machines using everyday items. For example, who can prop a door open (wedge), untwist 10 jar lids (screw), push a box up a ramp (inclined plane), or complete a lap by scooter (wheel and axle) the fastest? Who can lift the most weight with a pulley? Who has the best aim using a broom (lever) to sweep a ball into a goal?
  

Career Connection
“Our computer models capture and calculate different exercises, so we can see which have high force and high stress on the joints…Something that works for one person may not work for another, and that holds true for different surgical techniques, different exercises and different rehab programs.”

– Dr. Naiquan (Nigel) Zheng, Biomechanics 3-D Motion Analysis, Center for Biomedical Engineering and Science, UNC-Charlotte

MORE TO EXPLORE

Science Takes the Field – Spring Break at the Science Mill, March 7-March 18, 2022

Explorer Zone: Incredible Ball Machine (Video + activities, games, career connections)

Seeing Inside the Human Machine (Video)