AP Physics C Lab: Newton’s Second Law

Objectives

  • Collect force and acceleration data for a cart as it is moved back and forth.
  • Compare force vs. time and acceleration vs. time graphs.
  • Analyze a graph of force vs. acceleration.
  • Determine the relationship between force, mass, and acceleration.

Materials

computer, Vernier computer interface, Logger Pro, Vernier Low-g Accelerometer, Vernier Force Sensor or WDSS in place of sensors and interface, low-friction dynamics cart, 0.500 kg mass

Newt2 law

Preliminary questions

  1. When you push on an object, how does the magnitude of the force affect its motion? If you push harder, is the change in motion smaller or larger? Do you think this is a direct or inverse relationship?
  2. Assume that you have a bowling ball and a baseball, each suspended from a different rope. If you hit each of these balls with a full swing of a baseball bat, which ball will change its motion by the greater amount?
  3. In the absence of friction and other forces, if you exert a force, F, on a mass, m, the mass will accelerate. If you exert the same force on a mass of 2m, would you expect the resulting acceleration to be twice as large or half as large? Is this a direct or inverse relationship?

Analysis

  1. Compare the graphs of force time and acceleration vs. time for a particular trial. How are they different? How are they the same?
  2. Are the net force on an object and the acceleration of the object directly proportional? Explain, using experimental data to support your answer.
  3. What are the units of the slope of the force acceleration graph? Simplify the units of the slope to fundamental units (m, kg, s).
  4. For each trial compare the slope of the regression line to the mass being accelerated. What does the slope represent?
  5. Write a general equation that relates all three variables: force, mass, and acceleration.