A planar object comprises of two masses joined by a linear spring with relaxed length p. The horizontal and the vertical displacements of the two masses are measured relative to a fixed point of reference as shown in the figure. What would be the potential energy of the spring?
My initial guess...
Suppose a fly/mosquito is flying along with a moving truck. If the fly is outside the truck, then the fly has to move forward to keep up with the truck. What if the same fly was inside the truck. Will it have to move forward inside the moving vehicle just so that it is seen at the same position...