Rube Goldberg was an engineer, cartoonist, and inventor who lived in the United States in the 20th century. One of the reasons that Goldberg apparatuses are beneficial by engineering and physics educators, is that they exhibit many essential scientific principles.
These principles involve the conservation of momentum and conservation of energy, and concepts regarding the forces, which are essential in the generation of any engineering apparatus.
When an object hits another in a Rube Goldberg machine, this is an illustration of the conservation of momentum taking place. According to the conservation of momentum, momentum is neither destroyed nor created, it only moves from one object to another.
All Rube Goldberg instruments also demonstrate the conservation of energy. Conservation of energy illustrates that energy is neither created nor destroyed, it only travels from one place to another, or transfers from one kind to another.