A2L Item 168

• Description: Estimate the average acceleration for a specified time interval from an acceleration/time graph.
• Goal: Interpreting graphs
• Source: CT151.2-5
• Keywords: Acceleration, Graphing, Mechanics

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The question for students:

An object’s motion is described by the graph above. The average acceleration during the first 10 s is most nearly…

1. 0 m/s²
2. 20 m/s²
3. 30 m/s²
4. 40 m/s²
5. 50 m/s²
6. Other

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Commentary for teachers:

Answer

(3) Students may have difficulty understanding what they are asked. Recasting the problem in terms of areas helps. The only contenders should be #2 or #3. Counting blocks should make it clear that the result is much closer to #3.

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