Summary: solving the stretch of track on object is of a class of frequently asked questions, which involves a formula, select the appropriate reference systems, can make the solution process simple and clear.
Abstract: Solving rail stretch is a class of objects common problems, which involves the formula, select the appropriate reference system, you can make the solution process concise, clear.
Abstract: the elastic solution trajectory on the object is a common problem, which involves the formula, select appropriate reference system, can make the solving process is concise, clear.