Newton’s Second Law

Overview: These two lessons focus on the concept of net force in determining the acceleration of objects in free fall.  This concept is deceptively difficult for many students resulting in widely studied misconceptions such as the “motion implies force” misconception.

Lesson Objectives

Curriculum Context

Systems Thinking Concepts

  • Students will be able to describe, qualitatively, the motion of a sky diver as she falls and reaches terminal velocity.

  • Students will be able to describe, qualitatively, the direction and magnitude of the net force and acceleration of the sky diver as she opens her parachute.

  • Students will be able to hypothesize correctly about the nature and magnitude of the forces acting on an object  

  • Students will be able to solve quantitative problems, using Fnet=ma and kinematics relationships, involving the action of one or multiple forces.

  • Students will be able to state how the computer model aided their understanding of the forces involved in projectile motion.

These lessons are designed for a trigonometry-based, 11th-12th grade physics class. The National Science Education Standards state that students should understand that models are tentative schemes or structures that correspond to real objects, events, or classes of events, and that have explanatory power. Models help scientists and engineers understand how things work. Models take many forms, including physical objects, plans, mental constructs, mathematical equations, and computer simulations.


  • Accumulations

  • Rates

  • Flows

  • Interdependence




Systems Tools

  • Computer Model

  • Related worksheets

45-50 minutes per lesson and 20 minute follow-up

  • Computer Model

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