How to make physical objects interact, is the basis of the FIRST challenges. The challenge may include lifting, tossing or kicking an object, such as a ball. It may include moving the robot over or under challenges. The team uses mechanical devices to apply the properties of physics to successfully achieve these goals.

In robotics, mechanics primarily deals with two main applications. First is structure (see vocabulary section for more information). This is the framework upon which all other parts are attached. Deciding a robot’s structure has to consider the physical factors of the materials, such as weight, strength, flexibility, etc. and how any movement will cause strain on those materials. The second area is motion (see vocabulary section for more information). Mechanical devices usually create either some kind of movement within the machine itself or an action applied to an object outside the machine.

There are many physics properties that have to be taken into account when designing and building a robot. One is center of mass. This is not the center of the height, width and length of the robot, but instead is the balance point. In simplest terms it is a function of height and weight. For example, you can lower the center of mass in two objects of the same height, by putting heavier parts nearer the bottom.

Another property is friction. When parts touch, they ‘grab’ each other. In robotics, you may need to both increase and decrease friction. For instance, you add grease or bearings to a wheel and axle to decrease friction and allow quicker movement, but you may need to add friction to the surface of a wheel to provide grip or traction to maneuver over and around obstacles.

Also, when parts move, it applies a force on the structure, causing strain. Think of how a swing in motion, pulls the support bars back and forth as the swing moves. Stress or strain can be made and used on purpose. For example, if you stretch a rubber band, it will snap back into shape. This tension can be used to create a motion. Springs use compression to do the same thing. This is called elastic potential energy.

A machine is made up of parts designed to transfer a force from one place to another, maybe changing the direction or making the force bigger or smaller or delaying when it is applied. All machines use the same two basic simple machine families in their parts. See the test below for more information regarding simple machines.