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Kristin Murphy, Deseret News
Physics teacher Dennis Pedersen drops a pumpkin into a pumpkin catcher at City Academy in Salt Lake City on Wednesday, Nov. 8, 2017. The pumpkin catchers were designed by physics students at the charter school.

SALT LAKE CITY — Peering over the edge of the school roof, physics teacher Dennis Pedersen balanced an orange pumpkin in his arms and grinned.

More than a dozen students waited on the ground below with fingers crossed. With a quick countdown, Pedersen dropped the pumpkin from the two-story building.

High school seniors Erick Holloway and Shane Hepworth cheered as the pumpkin splashed into their homemade pumpkin catcher: a garbage bin full of water and laundry soap.

Hepworth fished the sudsy pumpkin from the bin.

"Water stops velocity," he explained, inspecting the pumpkin for damage. "If you can slow down something’s velocity, then the object is less likely to break."

"Laundry soap is much heavier than dish soap," Holloway added. "When you combine that with salt, it makes a much thicker density."

The physics class of high school students at City Academy in Salt Lake City designed several pumpkin catchers during the past week. On Wednesday they tested the catchers by dropping pumpkins from the roof above their classroom.

Junior Demitri Bergstrom used cardboard, a blanket, a pillow and a wooden frame to construct his pumpkin catcher. His 3-pound pumpkin smashed through the cardboard barriers but didn't crack after landing on the pillow.

"I kind of expected the small pumpkins to work," he said. "If I would’ve had a bigger (pumpkin) that worked, I would’ve been surprised."

Students brought their own pumpkins to drop, though each pumpkin had to weigh at least 3 pounds. If the pumpkin survived the drop, students were awarded extra credit for every additional 2 pounds.

"A lot of schools do egg drops, that’s fairly typical," said Principal Kevin Livesey. "This is kind of different, this is upscale."

Safio Hassan, Davona Dorsey and Mac Pyle also used a wooden frame cushioned with pillows. The group debated between using water or cushions for their design, Safio said.

"We didn’t really have any steps to it," Mac said. "It worked, and that’s what really matters."

For Pedersen, the best part of the assignment is after the pumpkin drop, when students file back inside to watch the video of the drops.

"Bigger pumpkins, more force," he explained. "We saw the bigger pumpkins were the ones that didn’t survive because they had the greater force."

This is the second year he has held a pumpkin drop at City Academy. He's seen many creative ideas in the past, including a group who caught a 28-pound pumpkin in a container of mashed potatoes.

"The ingenuity that goes behind it is something I really like," Pedersen said. "I’m very proud of the resources they put in."

This year, Claire Scoville and Maille Rollo used an idea Pedersen had never seen before. The two juniors strung several black garbage bags together and hung the bags from the roof using ropes.

Maille said the original idea was to stack actual garbage bins on top of one another, but the plan was too expensive.

"I think my favorite part was probably the free rein, but it was also the most intimidating part," Maille said.

"We wanted to do something a little crazy," Claire agreed. "We were a bit ambitious."

Many of the pumpkins survived the fall, but a few smashed into the ground or broke through the catchers.

"We’re trying to get rid of pumpkins anyway, so why not get some educational value out of it?" Pedersen said.