Kids Learning · science · ages 7-11
The Science of Roller Coasters
How a roller coaster runs without an engine, what a launch does, and why your tummy floats on the drop.
Roller coasters might feel like magic, but they are really a big science experiment you can ride!
Up the hill: storing energy
On most coasters, a chain or cable pulls the train slowly up the first hill: click, click, click. The higher it goes, the more stored energy (scientists call it potential energy) it has. Think of it like stretching a rubber band.
Down the drop: let it go!
At the top, the chain lets go and gravity takes over. As the train falls, stored energy turns into moving energy (kinetic energy). The bigger the drop, the faster you go. Most coasters have no engine on the train at all: after the lift hill, gravity does the work!
Why the hills get smaller
The wheels rub on the track and the train pushes through the air. That rubbing (friction) and the air resistance take away a little energy all the time. So every hill after the first has to be a little lower, or the train couldn’t make it over.
Launch coasters
Some coasters skip the big hill and launch you instead. Slinky Dog Dash in the video below has two launches! Many launch coasters use strong magnets along the track that push the train forward, fast.
Why your tummy floats
On a drop, you and the seat fall together, so you press on the seat less than usual. Your body notices you feel lighter, and that’s the floaty “butterflies” feeling. Scientists call it airtime.
Try this at home
Build a marble coaster with a pool noodle cut in half (ask a grown-up to cut it) or paper towel tubes. Start the marble from different heights. Does a higher start make it go farther? What’s the tallest loop it can make it around?
Watch and look closely
Check what you learned
On most roller coasters, what pulls the train up the first big hill?
A chain or cable pulls the train up the lift hill. After that, gravity does almost all the work.
What kind of energy does the train have at the very top of the hill?
Being high up stores energy. On the drop it turns into moving (kinetic) energy, and that's what makes it fast.
Why is each hill a little lower than the first one?
Friction and air resistance take away a little energy all the time, so the hills have to get lower.
A launch coaster starts fast without a big hill. What does it use?
Many launch coasters use powerful magnets (linear motors) that push the train along the track.
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