## Key Idea: A moving object will maintain the same speed and direction of motion unless a force acts on it.

*Students are expected to know that:*

- If no forces (or forces that add to zero) act on a moving object, then the object will maintain a constant speed.
- If an object is maintaining a constant speed (or is at rest), then no forces (or forces that add to zero) are acting on it.

*Boundaries*

- Students are expected to analyze situations involving no more than two forces acting on an object at the same time, and each force must act along the objectâ€™s line of motion.
- Items will not include situations in which objects are at rest.

Item ID Number |
Knowledge Being Assessed | Grades 6–8 |
Grades 9–12 |
Select This Item for My Item Bank |
---|---|---|---|---|

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It is possible for an object to be moving at constant speed without a force pushing or pulling it. | See the Original Project | |||

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Misconception |
Student Misconception |
Grades 6–8 |
Grades 9–12 |
---|---|---|---|

A constant force is needed to keep an object moving at constant speed. | See the Original Project | ||

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See the Original Project | |||

See the Original Project |

Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.