The goal of this activity is for students to discover that the total momentum of a system is constant when all the forces on the system are internal to the system. In the Preliminary Observations, students observe a number of collisions between two dynamics carts. Students identify the system to be investigated and list factors that may influence the momentum of that system. Students then design an experiment to examine the momentum of the system of two carts before and after the collision.


  • Identify variables, design and perform investigations, collect data, analyze data, draw a conclusion, and formulate a model based on data from the investigation.
  • Determine momentum and total momentum, based on velocity and mass measurements
  • Create a mathematical model of the relationship between initial total momentum and final total momentum.