Objectives After completing Unit 8: Friction and Traction, you will be able to: Explain the difference between static and kinetic friction and list the factors which determine traction. Create a VEX tire in Autodesk Inventor Professional. Have a robot ready to compete in a “tractor pull” and be proficient in making simple modifications to VEX robots. Take advantage of the principles of friction and traction to modify a robot to pull a greater amount of weight.

Coefficient of Friction: The ratio of maximum frictional force between two surfaces to the force holding them together. Term used to describe the "grippyness" of two surfaces meshing together. Slippery objects have a very low coefficient of friction.

Dimension: Parametric dimensions that control sketch size. When dimensions are changed, the sketch resizes. Dimensional constraints may be expressed as numeric constants, as variables in equations, or in parameter files.

Friction: The resistance that one surface or object encounters when sliding against another.

Kinetic Friction: The frictional force which opposes the motion of an object while it is moving.

Static Friction: The frictional force that opposes the motion of an object before it starts moving.

Traction : The friction between a, wheel, and the surface it moves upon. The amount of force a wheel can apply to a surface before it slips.

Tread The pattern on the surface of a tire.

Have a robot ready to compete in a “tractor pull,” where you can apply the lessons on friction and traction from the Unit 8: Think Phase. Make simple modifications to VEX robots.

Carry out pages 8-27 to 8-34 and 8-35 to 8-37

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