Final answer:
The question contains a mix of geometry and physics concepts, and with the given information, it is not possible to determine the length of the side opposite the 60° angle in the triangle. Additional information or clarification of the question is needed.
Step-by-step explanation:
In order to find the length of the side opposite the 60° angle in a triangle, we would typically use the principles of trigonometry, specifically the sine or cosine rules if it is a non-right triangle, or trigonometric ratios if it is a right triangle. The information provided in the question seems to be mixed with physics-related concepts (like magnetic fields and work against friction) which are not directly relevant to solving a geometric problem about triangle side lengths. Therefore, with the data given, it is not possible to determine the length of the side opposite the 60° angle. It seems there may be an error in the question or additional information is required.