## Key Idea: If a force acts on an object in the same direction as the direction of its motion, the object’s speed will continue to increase while the force is acting.

*Students are expected to know that:*

- If a force is acting on an object to push or pull it forward, the object will continue to move faster and faster in the forward direction the entire time the
force is acting.
- If an object’s speed is increasing, then a force must be acting on the object the entire time its speed is increasing.

*Boundaries***:**

- Students are expected to analyze situations involving no more than two forces acting on an object at the same time that act along the object’s line of motion.
Students are not expected to analyze situations in which the force is acting at an angle other than along the object’s line of motion, which would change the
direction of the object’s motion.
- Test items will involve situations in which forces are constant, not situations in which the forces are increasing or decreasing.

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.

NGSS Statements
Code |
Statement |

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

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

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

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

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

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

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