## Item FM069005: Use of tables of speed versus time, and information about forces acting on an object, to determine the object's speed at various times.

At 9 o’clock in the morning (9:00 am), an object is moving at a speed of 10 meters per second (m/s). It continues to move at that speed. At exactly 9:02 am, a single constant force begins to act on the object in the direction opposite to the direction of the object's motion. This force continues to act during the time shown in the table.

Time → | 9:00 am | 9:01 am | 9:02 am | 9:03 am | 9:04 am | 9:05 am | 9:06 am |
---|---|---|---|---|---|---|---|

Row A | 10 m/s | 10 m/s | 10 m/s | 9 m/s | 8 m/s | 8 m/s | 8 m/s |

Row B | 10 m/s | 10 m/s | 10 m/s | 10 m/s | 10 m/s | 9 m/s | 8 m/s |

Row C | 10 m/s | 10 m/s | 10 m/s | 9 m/s | 8 m/s | 7 m/s | 6 m/s |

Row D | 10 m/s | 10 m/s | 10 m/s | 10 m/s | 7 m/s | 7 m/s | 7 m/s |

Which row of the table shows what the object’s speed could be each minute? Assume that if a change in speed has occurred, the change is shown in the table.

- Row A
- Row B
- Row C
- Row D

- Distribution of Responses

- Students Responding Correctly

Group | Correct | Total | Percent |
---|---|---|---|

Overall | 937 | 1722 | 54% |

Grades | |||

6–8 | 576 | 1104 | 52% |

9–12 | 361 | 617 | 59% |

Gender | |||

Male | 478 | 844 | 57% |

Female | 450 | 853 | 53% |

Primary Language | |||

English | 879 | 1587 | 55% |

Other | 43 | 99 | 43% |

- Disciplinary Core Ideas
- PS2.A The motion of an object is determined by the sum of the forces acting on it; if the total force on the object is not zero, its motion will change. The greater the mass of the object, the greater the force needed to achieve the same change in motion. For any given object, a larger force causes a larger change in motion.

PS2.A Newton's second law accurately predicts changes in the motion of macroscopic objects.