A retired engineer is demonstrating a model of a gear system at a museum. The small gear has 12 teeth and rotates at 60 RPM. It drives a larger gear with 48 teeth. What is the rotational speed (in RPM) of the larger gear?

Sun, 03 May 2026 10:45:44 +0000

**A retired engineer is demonstrating a model of a gear system at a museum. The small gear has 12 teeth and rotates at 60 RPM. It drives a larger gear with 48 teeth. What is the rotational speed (in RPM) of the larger gear?** When visitors gather around interactive engineering exhibits, simple mechanical principles reveal surprising insights—like how gears shape rotational motion in fascinating ways. A small gear spinning at 60 revolutions per minute fuels curiosity when it drives a larger companion gear, sparking the question: what happens to speed when shifting from a smaller to a bigger gear? This isn’t just a classroom demo—it’s a real-world principle collectors and makers explore daily, particularly in hobbyist circles and STEM education. People are increasingly drawn to hands-on understanding of mechanics, driven by trends in DIY innovation and technical literacy across the U.S. A retired engineer showcasing this model at a museum illustrates a classic example of gear ratio in action. With a small gear sporting 12 teeth rotating at 60 RPM, it powers a larger gear with 48 teeth. This setup demonstrates fundamental gear relationships used in everything from machinery to robotics. The shift in speed isn’t intuitive at first—but understanding it offers practical clarity for those exploring machine design or simple engineering concepts. It’s a tangible lesson in how mechanical advantage influences motion. So, how does the larger gear respond? The rotation speed slows in direct proportion to the gear ratio. Because the driver gear has 12 teeth and the driven gear 48, the ratio is 12:48, simplified to 1:4. This means the rotational speed of the larger gear is a quarter of the smaller one—no trigonometry, just arithmetic. Dividing 60 RPM by 4 yields exactly 15 RPM. Thus, the larger gear rotates at 15 RPM.