At Valleyfair, 25 years of Physics Day

Thousands of high school students from more than 200 schools across Minnesota, neighboring states and Canada made Valleyfair Amusement Park in Shakopee their classroom this week. It's a yearly tradition known as Physics Day and this year marked the 25th year the amusement park hosted it.

On three days over the past week, the park invited school students to ride rides and measure the physics of them. How fast is that roller coaster going? How much force is being exerted in that drop? All very measurable items, when you're armed with a few worksheets, formulas and some simple tools to hold during the ride.

Students aren't forced to ride any ride they don't want to, but they have to ride something as part of the day's work: the carousel, a roller coaster, or the stomach-turning demon called the Enterprise.

David Rolfe, a Blaine High School senior, was holding an accelerometer--a clear plastic tube with a small weight dangling inside that measures the force of gravity--at the Enterprise.

"Where it's at right now is how much it's being pulled down by gravity normally," he said. "And if it meets the second line, that'd be like twice gravity."

That means you're getting pushed by twice the amount of gravity, Rolfe said.

The ride starts with everyone sitting in their own little compartments, spinning around in circles as if they were in those NASA machines that get astronauts used to extra forces of gravity. It looks like a Ferris wheel on its side.

Then in the middle of the ride, the whole contraption lifts up to a vertical position -- so as to resemble a Ferris wheel, except you're still spinning at that astronaut-like speed.

Blaine student Taylor Johnson took the accelerometer on the Enterprise. His job was to note where that little weight moves at certain points during the ride. So when you are vertical, for example, was the force of gravity higher at the bottom of that rotation, or the top?

"It went to about 1.75g at the apex of the ride," Johnson said, which means riders were being pushed 1.7 times the force of gravity.

Johnson and his classmates converged after the ride to gather all the little pieces of information each person was supposed to gather, so they could plug in all those numbers to formulas to determine things like acceleration and velocity.

Their teacher, David Ross, said Physics Day at Valleyfair is a fun way to end the school year, but that classroom stuff can't help but spill out here too.

"All year long we've been teaching them about mechanics - teaching them about friction and thermodynamics and pressures and fluids -- so all year long they've been working on all these topics, doing some labs, and then today is kind of a cumulative -- apply your knowledge in a fun setting," he said.

In another area of the park, another group of Blaine students had just finished riding the High Roller. It's a wooden roller coaster that dates back to 1976 when the park opened. Senior Curtis Graber was eye-balling estimates of the height of each hill on the ride and using times everyone recorded on stopwatches so they could figure out how fast the ride was going at various points.

"So, like the average speed for the entire track... because we know how long it is and how much time it took to complete the ride is 7.94 meters per second," Graber said. "That's the complete average of the entire track."

That translates to an average just under 18 mph, but Graber said they needed to calculate the speed at different points of the ride.

Paul Anderson, a physics teacher at Buffalo High School, considers the High Roller the best in the park. He said Physics Day is a big draw at his school.

"There are kids that sign up for physics just to take this," he said. "It's definitely one of those things they like to do. As a teacher, I like to make them do calculations and bring it back into the classroom."

Some of the students had video cameras with them, Anderson said.

"So they'll get video footage, they'll bring it back in and we'll do analysis of the video," he said. "They understand the concepts pretty well after they've been through the class. We take a little K'nex roller coaster in class, so we walk through how you're going to do it on the roller coaster when you get here - so they have a good idea of what they're going to measure when they're here."

But it's not back-breaking work, either. Anderson estimates his students could collect all the necessary data within the first hour of their visit. Since they can do all those final calculations later, that leaves them the rest of Physics Day to enjoy the outing. And it's a lasting memory.

"I'll go home tonight and I'll post this on Facebook and all my former students will say, 'Oh, yeah! I remember all that,'" Anderson said. "It's very much one of those things they like... You sneak in learning wherever you can... That's the job of a teacher."

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