Question

Describe the “energy story” for the situation below. Be sure to specify the system while including all the relevant energy transfers to/from the system, and transformations within the system. You should also 
indicate whether you think the the process described in the situation is reversible or not (as described in lecture, a qualitative way to determine whether a process is reversible would be to watch a recording of that process played backwards, and conclude whether that would normally occur in nature, e.g., seeing an egg unbreak would not be normal, which hints at the idea that the overall entropy of the universe increases).

A box is resting on the floor. You give it a push, and it starts to move. Friction acts on the box and brings it to rest.

Answer 1

initially the box is at rest hence the static frictional force is greater than that we are applying. As soon as the box moves the energy required to obercome the static friction is provided. Now when the block begins to move its velocity will increase hence the kinetic energy will increase. Now due to kinetic friction there will be an energy loss and to conserve the total energy the kinetic energy will decrease untill it becomes zero and friction energy increases.

the process is reversible