Massachusetts Comprehensive Assessment System

2018, High School Intro Physics

Question 44: Open-Response

Reporting Category: Motion and Forces
Standard: 1.6 - Distinguish qualitatively between static and kinetic friction, and describe their effects on the motion of objects.

A free-body force diagram for a heavy wooden bookcase at rest in a classroom is below.

Two students push the bookcase across the floor of the classroom.

Compare the amount of force needed to start the bookcase moving to the amount of force needed to keep it moving at a constant speed.
On the grid in your Student Answer Booklet, copy the free-body force diagram. Add to your diagram the horizontal forces acting on the bookcase when it is pushed at a constant speed. Include labels and use the grid squares to represent the relative magnitude of each force acting on the bookcase.
Identify one change to the bookcase or the floor that would affect the amount of force required to move the bookcase.
Explain how the change you identified in part (c) affects the amount of force required to start the bookcase moving or to keep it moving.

Scoring Guide and Sample Student Work

Select a score point in the table below to view the sample student response.

Score	Description
4	The response demonstrates a thorough understanding of static and kinetic friction, their effects on the motion of objects, and free-body force diagrams. The response correctly compares the force needed to start the bookcase moving to the force required to keep it moving, and includes a correctly drawn free-body diagram for the moving bookcase. The response also correctly identifies one factor that would affect the amount of force required to push the bookcase, and clearly explains how this factor affects the amount of force.
4
3	The response demonstrates a general understanding of static and kinetic friction, their effects on the motion of objects, and free-body force diagrams.
2	The response demonstrates a limited understanding of static and kinetic friction, their effects on the motion of objects, and free-body force diagrams.
1	The response demonstrates a minimal understanding of static and kinetic friction, their effects on the motion of object, and free-body force diagrams.
0	The response is incorrect or contains some correct work that is irrelevant to the skill or concept being measured.

Note: There are 2 sample student responses for Score Point 4.

High School Intro Physics

Question 12: Waves and Radiation

Question 23: Motion and Forces

Question 32: Heat and Heat Transfer

Question 44: Motion and Forces

Question 45: Electromagnetism

Return to the MCAS 2018 Student Work Directory

Last Updated: March 21, 2019