# Fifth Period

## First Time Here?

Go to the first strip and
see how it all started!

Join students Sophie, Tomás, Emma, and Marcus during Fifth Period! This STEM comic strip chronicles the exciting and often hilarious adventures of a close-knit group of four friends as they learn about science, technology, engineering, and math from their kooky, inspiring, off-the-wall science teacher, Mr. Kepler. When they're not in class, these kids love to explore the vast world of STEM on their own, launching weather balloons, programming computer games, and cataloging insects, sometimes with unpredictable and highly entertaining results!

Check back on the first and third Friday of every month for a new Fifth Period strip!

May 3, 2013

### Marcus Puts the Spin on Force

How is Marcus able to turn a bucket of water over his head without getting soaked? The same way someone can throw a ball over his head without it dropping on him. Objects that are moving want to keep moving in a straight line. Because gravity acts on objects all the time, though, they will follow an arc as they travel through the air on their own. If they move very fast, the arc looks almost straight, and if they move slowly, it looks more...archy.

In this case, Marcus uses the bucket to pull the water toward himself to make the water go around in a circle instead. The faster it goes, the harder he needs to pull toward the center (called a centripetal force) to keep it moving in a circle. Unfortunately for Mr. Kepler, the bucket handle breaks when it’s Emma’s turn, and both the water and the bucket “go ballistic” (remember that?) following the arced path instead...that leads to his head.

Try it yourself!

Next time you’re at a playground, take a spin on the merry-go-round. Notice how you need to pull yourself toward the center to keep your body going around in a circle, and you have to pull harder the faster you spin? You’re using centripetal force!