How many times have you said, “I wish the days were longer”? Well, NASA scientists say the construction of China’s Three Gorges Dam actually did make the days longer, by slowing the rotation of the Earth. Extra time you can use to learn a new language, catch up at work, or even better, sleep in. Did the dam actually make our days longer? Angular VelocityTo answer these questions, we need three basic physics ideas: (1) angular velocity, (2) angular momentum, and (3) the moment of inertia.