A falling ball viscometer is a device used to measure the viscosity of a fluid. It works by dropping a ball through a liquid and timing how long it takes to fall a certain distance. The viscosity can be calculated based on the ball's size, density, and the time it takes to fall, using Stokes' law. These viscometers are commonly used in laboratories and industries to assess the flow properties of various liquids, including oils and polymers. They provide a simple and effective way to determine viscosity without the need for complex equipment or procedures.