Reporting Category: Motion and Forces Standard: 2.3 - Describe both qualitatively and quantitatively how work can be expressed as a change in mechanical energy.

A student lifts a 10.0 kg box from the floor at a constant speed to a shelf that is 1.5 m above the floor.

Construct a free-body force diagram that represents the forces acting on the box when it is 1.0 m above the floor. Be sure to label your diagram.

Explain how you know that work is being done on the box, and how the work results in a change in the energy of the box.

Calculate the amount of work done on the box and the change in potential energy of the box. Show your calculations and include units in your answer.

Scoring Guide and Sample Student Work Select a score point in the table below to view the sample student response.

The response demonstrates a thorough understanding of free body diagrams and how work can be expressed both qualitatively and quantitatively as a change in mechanical energy. The response correctly constructs a free-body force diagram for the box. The response explains the evidence that shows work is being done and explains how work results in a change in the box’s energy. The response also correctly calculates both the work done and the change in potential energy.

The response demonstrates a general understanding of free body diagrams and how work can be expressed both qualitatively and quantitatively as a change in mechanical energy.

The response demonstrates a limited understanding of free body diagrams and how work can be expressed both qualitatively and quantitatively as a change in mechanical energy.

The response demonstrates a minimal understanding of free body diagrams and how work can be expressed both qualitatively and quantitatively as a change in mechanical energy.