Weighted wood block dragged horizontally by force sensor.

Static versus Kinetic Friction. A block of wood attached to a force sensor is dragged across the lecture table. Measured force is recorded on the laptop and projected. As weights are piled on the block, the relationship between static and kinetic friction changes. Up to 4.5 Kg can be piled on and the block still dragged. Typical results, with 4 Kg heaped on the block: Static friction, 22N required to move block; kinetic friction, 10N required to keep block moving at constant velocity.