1) This is a photo of a fan. The gears inside the plastic hard cover are interlinked and work together at different speeds to get the fan blade moving.
2) This is a photo of a watch. A very commonly used instrument to tell time but is has the same principle, Gears. Turn at different speeds to shows seconds, minutes, hours.
3) This is a photo of a kitchen utensil. It is used to mixed things up. The gears inside work like (rack and pinions), as the handle is turned, the gears that are interlinked will turn at the speed you spin the handle.