AP Physics B Objectives

III.  Newton's Laws of Motion

  1. Static Equilibrium (First Law) Students should be able to analyze situation in which a particle remains at rest, or moves with constant velocity, under the influence of several forces.

  2. Dynamics of a Single Body (Second Law)
    1. Students should understand the relation between the force that acts on a body and the resulting change in the body's velocity so they can:

      1. Calculate, for a body moving in one direction, the velocity change that results when a constant force F acts over a specified time interval.

      2. Determine, for a body moving in a plane whose velocity vector undergoes a specified change over a specified time interval, the average force that acted on the body.
  1. Students should understand how Newton's Second Law, F = ma, applies to a body subject to forces such as gravity, the pull of strings, or contact forces, so they can:
      1. Draw a well-labeled diagram showing all real forces that act on the body.

      2. Write down the vector equation that results from applying Newton's Second Law to the body, and take components of this equation along appropriate axes.
  1. Students should be able to analyze situations in which a body moves with specified acceleration under the influence of one or more forces so they can determine the magnitude and direction of the net force, or of one of the forces that makes up the net force, in situations such as the following:
      1. Motion up or down with constant acceleration (in an elevator, for example)

      2. Motion in a horizontal circle, (e.g., mass on a rotating merry go round, or car rounding a banked curve)

      3. Motion in a vertical circle, (e.g., mass swinging on the end of a string, cart rolling down a curved track, rider on a Ferris wheel)
  1. Students should understand the significance of the coefficient of friction so they can:
    1. Write down the relation between the normal and frictional forces on a surface.

    2. Analyze situations in which a body slides down a rough inclined plane or is pulled or pushed across a rough surface.

    3. Analyze static situations involving friction to determine under what circumstances a body will start to slip, or to calculate the magnitude of the force of static friction.
     3.  Systems of Two or More Bodies (Third Law)

  1. Students should understand Newton's Third Law so that, for a given force, they can identify the body on which the reaction force acts and state the magnitude and direction of this reaction.

  2. Students should be able to apply Newton's Third Law in analyzing the force of contact between two bodies that accelerate together along a horizontal or vertical line, or between two surfaces that slide across one another.

  3. Students should know that the tension is constant in a light string that passes over a massless pulley and should be able to use this fact in analyzing the motion of a system of two bodies joined by a string.

Made 25 July 2006
by Lori Andersen.
Document made with Nvu