## Item FM103001: Use of tables of speed versus time, and information about forces acting on an object, to determine the object's speed at various times.

An object is moving. Every second, the object’s speed is measured. When the clock reads 0 seconds, the object’s speed is 20 miles per hour (mi/hr). When the clock reads 2 seconds, a single constant force begins to act that slows the object down. This force continues to act during the time shown in the table.

Clock → | 0 seconds | 1 second | 2 seconds | 3 seconds | 4 seconds | 5 seconds | 6 seconds |

Row A | 20 mi/hr | 20 mi/hr | 20 mi/hr | 20 mi/hr | 20 mi/hr | 18 mi/hr | 16 mi/hr |

Row B | 20 mi/hr | 20 mi/hr | 20 mi/hr | 18 mi/hr | 16 mi/hr | 16 mi/hr | 16 mi/hr |

Row C | 20 mi/hr | 20 mi/hr | 20 mi/hr | 18 mi/hr | 16 mi/hr | 14 mi/hr | 12 mi/hr |

Row D | 20 mi/hr | 20 mi/hr | 20 mi/hr | 20 mi/hr | 14 mi/hr | 14 mi/hr | 14 mi/hr |

Which row of the table could be a correct representation of the object’s speed between 0 seconds and 6 seconds? Assume that if a change in speed has occurred, the change is shown in the table.

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

- 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.