Roughly one year ago, Tom Stanton constructed a trebuchet to launch projectiles (tennis balls) high into the air. While most would consider this to be a very fun accomplishment and move on, in his latest video, Stanton not only gives us a primer on how kinetic and gravitational potential energy works, but builds a device to actually measure how high his trebuchet hurls projectile.
The height measurement unit is shaped like an oversized golf ball, containing an altimeter, battery and Arduino Nano, along with an an accelerometer to detects launches. Four seconds after being flung into the air, one compartment of the golf ball pops open and deploys a parachute via an ingenious rubber band and servo mechanism. Landings appear to have been quite soft, so much so that the parachute was made smaller to avoid excessive drift.
After measurement, it turns out that the trebuchet is able to launch the measurement projectile around 60 meters, or roughly 200 feet. While this is impressive — and certainly fun to watch — Stanton calculates that his machine is only about 35% efficient at transferring energy, or perhaps a bit more when air resistance is taken into account. Even so, it’s a really fun design, and a great lesson on how while understanding physics concepts is important, so is real-world experimentation!