MythBusters Episode 120: Seesaw Saga

A skydiver whose parachute fails to open can hit the high end of a playground seesaw, landing on his feet, and launch a child on the low end safely up to the roof of a 7-story building.

busted

In their first test, Adam and Jamie constructed a steel seesaw and placed a dummy on one end whose weight matched that of an average 6-year-old girl. To approximate the effect of a skydiver hitting the high end at terminal velocity, they calculated the proper combination of weight and height and dropped several water-filled barrels. The impact crushed the seesaw, ruptured the barrels, and launched the dummy to a height of 20 feet (6 m). Adam and Jamie went on to design and built a seesaw that could effectively deliver the energy of the falling skydiver to the girl without buckling.

The Build Team was brought in to further analyze the terminal velocity based on a specific type of skydiving suit and the diver’s body position; the determined it was 122 miles per hour (196 km/h). They also built a rig with bungee cords and guide wires that could accurately propel a dummy diver onto the target at the right speed. The child dummy was outfitted with “shock watch” stickers to measure the forces exerted on it. Three drops were carried out.

• 1st drop: diver hit slightly off-center and burst on impact; girl flew 55 feet (17 m) up and 70 feet (21 m) laterally, but suffered enough force to kill her
• 2nd drop: sand-filled inner tube used for diver; girl hit the guide wires
• 3rd drop: girl flew 130 feet (40 m) up at an angle (equivalent of 200 feet/60 meters straight up), but experienced a g-force of 42 g which would cause serious injury even before she hit the ground

Based on the need for a super-strong seesaw and the injuries inflicted on the girl, the team declared the myth busted.