Before Wednesday, the thought of roller coasters triggered general premonitions of fun for Emily Moscrip: Calamitous drops, shriek-inducing turns, limbs buckled with preparation as screeching machinery swept her away from the Earth.

But on the sunny afternoon, a new aspect of roller coasters had manifested in her 18-year-old mind: F = ma.

Peering over the calculator held by fellow Lewiston High School student Austin Hurd, Moscrip reasoned how much power was needed to carry a loaded train up a Silverwood Theme Park ride.

Not usually her first concern on a ride, she acknowledged.

"I've never thought about like the science behind it," said Moscrip as rides roared in the distance at the Athol park. "I've always just thought about riding them."

Moscrip was among roughly 2,800 students who converged at Silverwood on Wednesday for the park's annual Physics Day. The event discounted prices to teens from 73 high schools across the Northwest, in return for a little mental exercise.

With the purpose of coaxed perspective, students at Silverwood were charged with scrutinizing the math and physics behind each rumbling ride.

Teens were provided a mess of figures to sew into an equation, like a ride's lift hill height, the length of the ride and mass of the seats.

Afterward, students were free to test the lesson by enjoying all the park's rides for the day.

"We get to experience physics firsthand," said Lewiston High School teacher Rachel Evans. "We do work with (model) carts in class, but here we get to actually experience it."

Students from Priest River Lamanna High School pointed out the advantages of the working roller coaster models they had created for the event, which would be judged by Silverwood staff.

The models required applying knowledge of angles, momentum and factors impacting speed, said Anna Hurst, 18.

"We've been in physics all year, and now we're taking the things we learned and using them," Hurst said.

Besides reinforcing the year's curriculum, navigating the roller coaster equations boosted her confidence that real life rides will run their intended course, she said.

"It does make me feel safe to know somebody has put time and thought into working it," Hurst said. "We didn't have issues with (our model) coming off the track."

"We did," lamented Priest River student Tyler Wilson, 17, of his and his partner's model, boasting several steep curves. "People died a lot."

Students on Wednesday also observed robotics work conducted by 4-H team the Techno Tornados on the Silverwood campus.

The event is intended as community outreach, said Silverwood Spokesman Layne Pitcher.

"Silverwood is always looking for good ways to give back," Pitcher said, adding that Physics Day, as well as Science Day for younger students, helps the theme park prepare for the season ahead. "It gives (students) the opportunity to do something fun and learn at the same time."