Summary: solving the stretch of track acting on an object is a class of frequently asked questions, involving the formula f = Ma, selecting the appropriate reference systems, can make the solution process simple and clear.
Abstract: Solving rail stretch is applied to a class of objects common problems, which involves the equation F = ma, choose the appropriate reference system, you can make the solution process concise, clear.
Abstract: the elastic solution of orbital interaction on the object is a common problem, which involves the formula F=ma, select the appropriate reference system, can make the solving process is concise, clear.