Package of tamale slides along a floor with speed . It then runs into and compresses a spring, until the package momentarily stops.
SOLUTION: A starting Key Idea is to examine all the forces acting on the package, and then to determine whether we have an isolated system or a system on which an external force is doing work.
System: The package spring-floor-wall system includes all these forces and energy transfers in one isolated system. Therefore, a second Key Idea is that, because the system is isolated, its total energy cannot change.
Rearranging and substituting known data give us