More information about the PTRA program

Dynamics: Forces and Motion

This topic is broken into units to help in formulating cohesive, effective lessons. Clicking on each unit title below will display appropriate activities, lesson plans, or labs.

Unit materials are a subset of all possible materials available for this topic, selected especially with the new physics teacher in mind. You may instead browse all materials for this topic here.


Physics First Dynamics: Forces and Motion Units

A branch of mechanics that deals with forces and their relation primarily to motion but also sometimes to the equilibrium of bodies. Units are not listed in a prescribed order.

  Newton's First Law & Inertia (21)

Lesson Plans:

Multimedia 3-day Lesson Plan                        Grades 6-9
Galileo's classic experiments on gravity and inertia are presented in an entertaining multimedia format.  Includes full standards-based lesson plan, four short videos, an interactive simulation, and printable instructions for a classroom pendulum experiment.  Excellent resource to pave the way for future understanding of Newton's Laws.  (Open Website)

Hands-on Experiments                               Grades 9-12
A set of seven experiments on the Law of Inertia, developed by a team of scientists and educators in the UK.  Each experiment has been classroom-tested and focuses on practical applications of the concepts to be presented.  Contains full instructions for set-up, safety information, and tips for teachers.  (Open Website)

Lesson Plan: 50 minutes                                                      Grades 11-12
This unique lesson helps students understand that inertia is an inherent property of matter, while weight depends on gravity.  Using simple and inexpensive objects, students make mass measurements without the use of gravity, similar to the measurements made aboard the Skylab space mission.  (Open Website)


Activities:

Lab                        Cooperative Learning                          Grades 9-12
This full lab manual encourages critical thinking by using a "Socratic Method" of inquiry.  Students must consider opposing and contradictory views, engage in active dialog about given problems, and defend their own conclusions.  This lab covers Newton's First Law (inertia) and Third Law (action/reaction).  (Open Website)

Problem-Based Learning Activity (PBL)                            Grades 9-12
Great classroom activity to get students thinking about the Law of Inertia, force interactions, and conservation of momentum as they solve a real-life problem to determine which driver is at fault in a car accident.  See link below under Content Support to read more about the pedagogy behind Problem-Based Learning.  (Open Website)

Teacher Demonstration                                                  Grades 6-12
Cool classroom demo for illustrating inertia at rest.  A dollar bill is placed between two soda bottles; the top bottle is filled with water.  Upward/downward forces are balanced because the dollar acts as a sealant.  Quickly removing the dollar bill creates a net unbalanced force on the water, which whooshes into the soda bottle below.  Try teaming this teacher-led demo with the Pencil Drop below, which students could perform.  (Open Website)

Classroom demonstration                                             Grades 6-12
A great companion to the "Dollar Bill Grab" above.  This demo illustrates the same basic concept (Law of Inertia).  If done correctly, it looks like a magic trick.  Even if done incorrectly, it still demonstrates the idea of inertia at rest.  Could be a good springboard for cooperative learning groups to discuss the meaning of net force, and what happens when net force is zero.  (Open Website)

Interactive Demonstration                                            Grades 6-12
This animation by the UCLA Demoweb shows how to set up an unusual demo featuring a heavy ball suspended by a string, with a string attached to the bottom.  It provokes thought about the Law of Inertia.  A quick jerk will break the lower string; a slow and steady pull will break the upper string.  (Open Website)

Interactive Demonstration                                             Grades 6-12
What would happen if an object in circular motion suddenly loses its net centripetal force?  Teachers can easily set up this demo to show students that Newton's Law of Inertia will govern the situation, and the object will fly off in a straight line tangential to the circular path.  Pair this item with the animation below titled "Physlets In-Class Exercises-Circular Motion".  (Open Website)

Interactive Simulation                                                  Grades 6-9
This collection of applets explores the physics of force and momentum through simulations of a spaceship moving through space.  Students learn about inertia in motion and conservation of momentum as they fire the engines and navigate around simple obstacles.  (Open Website)

Simulation/Animation                                                  Grades 6-12
Excellent resource for students to explore inertia in motion, as they engage any combination of four engines that exert forward or reverse thrust on a space telescope traveling at constant velocity.  Part of the Open Source Physics project.  (Open Website)

Concept Question: Animation                                        Grades 6-12
Great warm-up exercise for an in-class discussion of uniform circular motion and the law of inertia.  A ball is swung on a string in a circular path.  What happens when the string breaks?  Students choose from five animations that represent possible results.  Team this applet with the classroom demo above titled "Partial Pie Plate".  (Open Website)


Content Support For Teachers:

Pedagogy
Problem-Based Learning (PBL) is an instructional method that presents authentic, life-like situations to engage students in learning.  Click here to read more about the pedagogical basis of PBL and how to implement it in the physics classroom.  This site also features several PBL scenarios developed for introductory physics students (many are appropriate for high school).  (Open Website)

Educator's Guide
Beginning students can usually quote Newton's First and Third Laws, but struggle to understand what they really mean.  This educator's guide, created by the respected Modeling Instruction project at Arizona State University, gives teachers in-depth support for developing a research-based unit on inertia and interactions.  For more on the Modeling Instruction pedagogy, see the resource below.  (Open Website)

Curriculum
This chapter from The Book of Phyz offers rich curriculum support for teaching about the Law of Inertia.  It features well-written background information for teachers, related activities and experiments, and a unit test with answers.  Don't miss "The Clever Dumbbell" and the "CD Glider" project.  (Open Website)


Student Tutorials:

Comprehensive Student Tutorial                                   Grades 11-12
Beginning students gain an in-depth, yet entertaining view of the background and applications of the Law of Inertia.  Through animations and self-guided problems, this tutorial helps students understand the idea of unbalanced force and see that mass is a measure of the amount of inertia.  (Open Website)


Assessment:

Homework Problem/Performance Assessment                         Grades 11-12
An assessment to help teachers determine whether students understand the relationship between mass and inertia.  This alternative homework problem, based on physics education research, presents students with a real-life situation about highway stopping distance and the related physics.  (Open Website)

Student Worksheet/Graphics Assessment                                   Grades 11-12
This worksheet accompanies the Modeling Instruction unit on Inertia and Interactions (see Content Support above).  It shows 18 drawings of a block-like object, which experiences various types of motion or remains at rest.  Students must sketch all forces acting on the block in each scenario.  Assesses understanding of the basic fundamentals of Newton's First Law and the ability of the student to draw force diagrams.  (Open Website)

Unit Test/Summative Assessment                                            Grades 11-12
A comprehensive set of questions that accompanies the Modeling Instruction Educator's Guide for Inertia and Interactions (see link above in Content Support). It could be used as an informal homework set or as a unit test.  This item assesses the ability to interpret and create force diagrams, solve problems related to equilibrium and net external force, and apply the Law of Inertia in objects at rest or in constant velocity.  (Open Website)

Concept Question: Formative Assessment                                        Grades 6-11
A simulation-based problem to spark student discussion about inertia and force interactions.  A  puck traveling on a frictionless air hockey table is given a momentary push.  What is the resulting path of its motion?  Pair this applet with the one below on sustained push.  Assesses student understanding of how resultant motion is affected by the type of force applied.  (Open Website)

Concept Question: Formative Assessment                                        Grades 6-11
A simulation-based problem that supplements the problem above on momentary push.  A satellite is floating at constant velocity when its thrusters engage.   The resulting path of its motion will differ from the example above.  Assesses student understanding of how resultant motion is affected by a sustained force produced by thrust.  (Open Website)


  Newton's Second Law & Net Force (6)

Lesson Plans:

Inertia is proportional to mass, weight is also proportional to mass, too, so both go together. The difference is that inertia is an inherent property of matter, while weight also depends on gravity.  (Open Website)


Activities:

This simulation illustrates Newton's Second Law of Motion by showing the reaction of a rolling car by increasing its mass and acceleration.  (Open Website)

This simulation demonstrates motion of a block being pulled up an incline plane at constant velocity by a spring.  By changing the angle of inclination, mass, and coefficient of friction, students can better understand the forces that interact to move an object up a hill.  Click on Force Vectors and pause the simulation to see an instantaneous vector diagram.  (Open Website)

In this interactive simulation, an object sliding on a horizontal surface is connected by a string to a hanging mass. Students can set the value of the two masses and the coefficient of friction.  The simulation also features a timer for gathering accurate data as the slider moves.  (Open Website)


Student Tutorials:

This student tutorial illustrates how circular motion principles can be combined with Newton's Second Law to analyze physical situations.   Two algebraic problems and detailed solutions are provided, plus a five-step model for solving circular motion problems.  (Open Website)

This comprehensive, high-school-friendly tutorial  includes background on the principal forces encountered in Newtonian frameworks, an explanation of free body diagrams, example problems, a self-test, and a related simulation.  (Open Website)


  Newton's Third Law (1)

Activities:

One of the guiding ideas of physics is the Law of Conservation of Linear Momentum.  When the external forces acting on a system equal zero, the linear momentum remains constant.  This concept is fully explored in these lecture materials, which include problems involving both elastic and inelastic collision.  These concepts help students build a framework for understanding the nature of atomic and subatomic phenomena.  (Open Website)


  Applications of Newton's Laws (5)

Lesson Plans:

This is a lesson plan incorporating 11 activities for beginning physical science students. The lesson helps students conceptualize everyday experiences in terms of Newton's Laws.  (Open Website)

This resource directs teachers in the set-up of 20 engaging demonstrations relating to motion/mechanics.  The materials include motion in one and two dimensions, coupled pendulum motion, rotational motion, and more.  The author selected each demonstration for its "attention-getting" appeal and its ability to provoke thought about specific mechanical processes.  It is part of a larger collection.  (Open Website)


Activities:

This lab activity has students create a pendulum with a one second period. Students must explore the importance of physical properties, such as length of the string and mass of the bob, to determine what they affect the period.This is a part of a PTRA manual on Kinematics and Motion.  (Open Website)

As students use the mouse to move objects of varying mass along a 1-D path, the simulation charts P-T, V-T and acceleration graphs.  Applied force, friction, and gravitational constants can be varied in this interactive activity.  (Open Website)


Student Tutorials:

For the teacher planning a unit on amusement park physics, this tutorial can double as a student classroom activity.  It offers an excellent overview of the forces acting upon a roller coaster as it travels on a straight, curved, or looped track.  It includes a self-test at the end to gauge student comprehension.  Free body diagrams and animations depicting kinetic/potential energy also enhance student understanding of a complex set of interactions.  (Open Website)


  The Universal Law of Gravitation (2)

Lesson Plans:

This lesson plan recreates Newton's result. This is a lesson plan for teaching Newton's formulation of gravity  (Open Website)


Content Support For Teachers:

This resource features well-organized text explanations alongside equations in a concept-building format for understanding gravitational interactions. Short problems and tables provide a concrete approach to helping students grasp the universal nature of gravitational attraction so that formulas make sense.  (Open Website)


  Frictional Forces (3)

Activities:

Applying the skills of teamwork, students work cooperatively to find out coefficients of friction for surfaces of metal on wood and metal on metal.  (Open Website)

This java applet shows the change in a force diagram and the reacting motion of a system when frictional forces are present.  (Open Website)

This simulation demonstrates motion of a block being pulled up an incline plane at constant velocity by a spring.  By changing the angle of inclination, mass, and coefficient of friction, students can better understand how frictional force affects the movement of an object on a hill.  (Open Website)


  Force Diagrams (1)

Student Tutorials:

This comprehensive, high-school-friendly tutorial  includes background on the principal forces encountered in Newtonian frameworks, an explanation of free body diagrams, example problems, a self-test, and a related simulation.  (Open Website)


  Rotational Motion (5)

Activities:

This applet presents the "Atoms and Rods" model.  With simple keyboard commands, students control the motion of the 2-D "pencil" and the 3-D "ball" to explore tension/compression of the rods.  (Open Website)

This simulation demonstrates the principle of lever and torque. Weights can be added or removed from different points on a balanced beam and the resultant tipping of the beam can be studied.  (Open Website)


Content Support For Teachers:

One of the most deeply entrenched misconceptions among beginning physics students is that centrifugal motion (away from the center) is a "force" in itself.   In this resource, part of Physics Classroom, the author explains why the direction of force is viewed from an inertial frame of reference in a classical mechanics course and thus why centrifugal motion is not a force in a Newtonian framework.  (Open Website)


Student Tutorials:

This student tutorial illustrates how circular motion principles can be combined with Newton's Second Law to analyze physical situations.   Two algebraic problems and detailed solutions are provided, plus a five-step model for solving circular motion problems.  (Open Website)

This resource guides the beginning student through characteristics of circular motion.  It is broken into five sections addressing:  the mechanics of circular motion, centripetal force,  algebraic and trigonometric problems and solutions, and a full chapter that debunks the centrifugal "force" misconception.  Interactive problems feature liberal use of diagrams and force vectors to enhance understanding.  (Open Website)


  Benchmarks and Standards (1)

References and Collections:

This resource is the Forces of Nature section of the Science Literacy Benchmarks published by the American Association for the Advancement of Science (AAAS).  It is a statement of desired learning outcomes on the topic of physical forces and interactions for grades 2, 5, 8, and 12.  (Open Website)