{"id":57869,"date":"2025-12-26T05:56:11","date_gmt":"2025-12-25T20:56:11","guid":{"rendered":"https:\/\/phys-edu.net\/wp\/?p=57869"},"modified":"2025-12-26T05:56:11","modified_gmt":"2025-12-25T20:56:11","slug":"visualizing-physics-with-a-flying-hammer-revealing-the-beautiful-path-of-the-center-of-mass-using-a-smartphone-app","status":"publish","type":"post","link":"https:\/\/phys-edu.net\/wp\/?p=57869&lang=en","title":{"rendered":"Visualizing Physics with a Flying Hammer! Revealing the Beautiful Path of the Center of Mass Using a Smartphone App"},"content":{"rendered":"

I am Ken Kuwako, your Science Trainer. Every day is an experiment!<\/strong><\/span><\/p>\n

\"IMG_7359\"<\/p>\n

Toss the Mallet! Channel Your Inner Hammer Bro!<\/b><\/p>\n

The Era of Easy Strobe Photography is Here!<\/h3>\n

Have you ever seen a strobe photograph<\/b>? If you open a science textbook, you will likely find pages showing a ball flying in a perfect arc or an athlete’s running form captured in a sequence of frozen moments. Have you ever wondered, “How on earth did they take that?” Traditionally, it requires a pitch-black room, a camera shutter left wide open, and a light that flashes\u2014pop, pop, pop\u2014at perfectly even intervals to burn each moment of movement into a single frame.<\/p>\n

While many of us have thought, “I want to try that!”, the need for specialized equipment and a darkroom usually meant it wasn’t something you could just do at home. But times have changed.<\/b> Nowadays, we have stop-motion and trace-path tools right on our iPhones. These apps can automatically detect moving objects in a scene and composite their path into one image. Today, I want to show you an experiment using one of these apps to uncover the beautiful laws of physics<\/b> hidden within complex motion.<\/p>\n

What You Need<\/h3>\n

A mallet<\/b> (a rubber mallet works too), electrical tape, and an iPhone app.<\/p>\n

Note: To avoid damaging your floors, use a hammer with a wood or rubber head. Please be very careful with your surroundings!<\/p>\n

The Method<\/h3>\n

First, let’s prepare. Find the center of gravity (the balance point)<\/b> of the mallet. Try to balance it on just one finger until you find the sweet spot. Wrap a piece of electrical tape<\/b> there as a marker. \"Screenshot<\/p>\n

Launch your iPhone app and get ready to shoot. It helps to have someone else act as the photographer.<\/p>\n

Tap the record button and toss the mallet so that it spins through the air. Feel like a Hammer Bro from Super Mario!<\/p>\n

After filming, adjust the “time interval slider” in the app to find the right balance so the images don’t overlap too much.<\/p>\n

\"IMG_7359\" 5. Print out the resulting image and use a pen to trace the path of the mallet’s center of gravity (the tape position)<\/b>. \"Screenshot 6. Overlay this with a quadratic curve (parabola)<\/b> like the ones you learned about in math class. That is it! Simple, right? (^^)<\/b><\/p>\n

You can see how it looks in action in this video. Notice how even though the mallet is spinning wildly, one specific point moves with perfect regularity.<\/p>\n