How do cell phone towers identify your location? Students describe geometrically the location information provided by a cell phone tower, explain why loci from at least three towers are required to pinpoint a customer's location, and consider the tradeoff between coverage and "locatability" when a phone company chooses a new tower location.
How do vehicles turn so smoothly? Students calculate the circumferences of circles to determine how far vehicles travel during a turn and explore the engineering that allows cars to turn so smoothly.
How fast is the Earth spinning? Students use rates, arc length, and trigonometric ratios to determine how fast the planet is spinning at different latitudes.