AP Physics B Objectives

   I. A: Kinematics

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AP Physics B Curriculum Page
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College Board Topic I:
Newtonian Mechanics

Topics:

  1. Kinematics (including vectors, vector algebra, components of vectors, coordinate systems, displacement, velocity, and acceleration)
    1. Motion in one dimension
    2. Motion in two dimensions, including projectile motion

Time Range:
6 weeks

Suggested Teaching Strategies:

  • Vectors
    Have students construct a three-force equilibrium on a force table or similar device, and construct graphical scale drawing showing how any two forces add vectorially to become the equilibrant of the third force (see Core Lab 2). Be sure to expand the concept to the generalization that perpendicular vectors do not affect each other's size; this idea is important in force analysis, circular motion, etc.

  • Displacement
    Use concept of "distance" when doing 1-dimensional motion lab and work; introduce "displacement" concept with the introduction of vectors. Distinguish between the distance you run in a circle back to your starting point (circumference) and your displacement (zero), etc. Stress that the various one-dimensional motion equations are actually vector equations where "d" is displacement, and thus can be negative. This is important in a variety of problems, including falling bodies and projectiles.

  • Velocity and Acceleration
    Have students collect data on an object undergoing constant acceleration, and plot distance vs. time and later speed vs. time graphs of the motion. A computer can help with the graphing and forming best-fit lines and curves, and you can relate the graphs to the one-dimensional motion equations. (See Core Lab 1.) Help students associate the slope of the d vs. t and v vs. t graphs with their physical meanings. (See Unit 1 Worksheet B in Inquiry Physics curriculum.) After inventing the two basic equations for average speed and the equation for acceleration, have the students use algebra to invent the remaining equations. (See Unit 1 Worksheet C in Inquiry Physics curriculum.),

  • Falling Bodies
    Demonstrate the concept directly. Examples range from the simple to the complex:
    • Drop a piece of paper and a small ball or rock and note their different rates of fall, have the students prompt you to crumple the piece of paper into a ball and note how the rates of fall become quite similar.

    • Use something like Pasco's free-fall apparatus to time to the nearest thousandth of a second the fall time for a ball dropped about 1.5 meters, and have the students calculate the acceleration rate; or use one of the older types of free-fall apparatus (e.g. using photogates or spark paper) to find the acceleration.

    • Arrange an ultrasonic motion detector underneath a protective grill and drop various objects; a connected computer or calculator can show the acceleration, graph the motion, etc. Discuss Galileo's logical argument for constant free-fall acceleration. (Tie a feather to an anvil: if Aristotle were right and heavier things fall faster, wouldn't the heavier anvil fall faster than the feather and thus be retarded by the slower feather? But then again, the feather and anvil combination are heavier than an anvil by itself, so wouldn't they fall faster than an anvil by itself? This logical paradox demonstrates the problem with the initial assumption that heavier things fall faster.)

  • Projectiles
    Pose these questions:
    • If one bullet was fired horizontally from a gun over a level field, and another bullet was simultaneously dropped from the same height, which would land first? Have students argue the possibilities and later demonstrate the answer is that they strike at the same time by using a Simultaneous Velocities Apparatus (or simply two marbles, one dropped while another is flicked off a tabletop).
    • An object is fired straight upward from a cannon that is mounted on a train moving forward at a steady velocity; where will the cannonball land? Have students argue the possibilities and later demonstrate the answer is that the cannonball lands back in the cannon (neglecting air resistance and wind) by using a Ballistics Cart.
    • If a banana is thrown at a monkey in a tree, but the frightened monkey lets go of a branch and falls at the same instant the banana is thrown, where does the banana go relative to the monkey? Have students argue the possibilities and later demonstrate that the banana strikes the monkey using a Monkey & Hunter Apparatus.
    Have students demonstrate their mastery of horizontal vs. vertical velocity graphs by acting out pre-set graphs you give them (see Kinesthetic Graphs activity in Inquiry Physics curriculum).

Aligned Resources:

Revision Date:
May 2001
ISD 30 Science Dept. Bartlesville Independent School District 30
Science Department

AP Physics B Curriculum