Feeling Weightless: Forces and Motion on a Roller Coaster

People love riding roller coasters. Amusement parks become crowded as soon as the weather is warm enough to ride super-fast rides. The only thing louder than the sound of the roller coasters are the happy screams of the people riding them.

Roller coasters are huge machines that change how forces are applied to our bodies. Forces are anything that push or pull. Forces move an object by speeding it up or slowing it down. These changes in speed are called accelerations.

Do you think roller coasters are scary because they go so fast? Well, think again! It’s not speed that makes people scream. Roller coasters are fun and scary because they make our bodies feel different. It’s all about forces!

Feeling Weightless

Larry Giles is the Vice President for Engineering at Busch Gardens amusement park in Williamsburg, Virginia. He’s spent a lot of time thinking about how people react to forces and motion.

“There’s a lot of different things you can use to create that ‘wow’ factor and that fun factor,” he says about amusement park rides. But one of the things people enjoy most is the feeling of weightlessness.

Gravity is one of the most important forces in our lives. Larry says it’s important to understand that we all feel gravity every moment of every day. Gravity is the force that pulls you down to Earth. It’s scary when we feel a change from that normal “pulling down” force.

Scientists and engineers refer to the force of gravity that we experience normally on Earth as “1 g.” Anything less than 1 g means a person feels lighter than they do normally. “People get really excited anytime they get anything less than 1 g of gravity, which is what you’re sitting at right now,” says Larry.

“When your body gets below 1 g, it starts perceiving that ‘hey! I’m falling!’” Larry said. “It automatically transmits a scare factor to your whole body going, ‘hey, this is not normal!’... So we try to create places in our rides that have less than 1 g and get close to 0 g,” he says.

But how do the engineers create this feeling?

That First Big Drop

“Where do you feel is the scariest part of the ride?” Larry asked. “It’s that first drop, right? Everybody says, ‘Oh wow, that first drop is so exciting.’”

Engineers design roller coasters to have different types of curves. Tight curves will put different forces on the riders than wide curves. One of the biggest curves on a roller coaster usually happens after the first hill.

The force of gravity is always pulling down. Engineers design this first curve to make a rider feel a force pointed up. “Vertical accelerations mean you’re getting uplift,” Larry said. “And that’s giving [a rider] airtime.” When the up force from the roller coaster matches the down force from gravity, the riders feel weightless.

“Those are the kind of things we try to create,” said Larry. “Things you aren’t used to feeling, and if you’re not used to feeling them, they do create excitement.”

On a roller coaster, forces are more than just physics. They’re a lot of fun!