Editor selections by Topic and Unit

The Physics Front is a free service provided by the AAPT in partnership with the NSF/NSDL.

Physical Sciences K-8: 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 (16)

Lesson Plans:

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.

Item Type: Multimedia Module
Level: Grades 6-9

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.

Item Type: Classroom Experiments
Level: Grades 6-12

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.

Item Type: Lesson Plan
Level: Grades 8-12

Activities:

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.

Item Type: Demonstration
Level: 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.

Item Type: Demonstration
Level: 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.

Item Type: Interactive Demonstration
Level: 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".

Item Type: Interactive Demonstration
Level: Grades 6-12

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.

Item Type: Interactive Simulations
Level: Grades 8-12

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.

Item Type: Interactive Simulation
Level: Grades 8-12

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".

Item Type: Concept Question/Animatio
Level: Grades 6-12

Content Support For Teachers:

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).

Item Type: Pedagogy
Level: Secondary teachers

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.

Item Type: Instructor's Guide
Level: Secondary teachers

This chapter from The Book of Phyz offers curriculum support for teaching about the Law of Inertia.  It features well-written background information for teachers, related activities and experiments.

Item Type: Content Support
Level: Secondary teachers

Student Tutorials:

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.

Item Type: Web-based Tutorial
Level: Introductory Physics

Assessment:

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.

Item Type: Formative Assessment
Level: Grades 6-12

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.

Item Type: Formative Assessment
Level: Grades 6-12

  Newton's Second Law & Net Force (7)

Lesson Plans:

This lesson plan for Grades 6-8, with printable student guide, is a great supplement to the PhET simulation Forces and Motion.  The winner of a PhET "Gold Star", it was developed by an experienced teacher to provide explicit guidance for students as they use the simulation to investigate force interactions. We like it because it provides just the right amount of help to navigate the simulation, while also allowing students to construct their own meaning from the model.

Item Type: Lesson Plan
Level: Grades 6-8

This archived lesson module challenges students to build a model spacecraft with certain constraints:  as light as possible, yet strong enough to withstand three "launch-to-orbit" trips. Kids will be exposed to engineering design, the physics of thrust and drag, and using systems analysis to solve problems. All materials are readily available at hardware or grocery stores. Meets multiple national standards in science, mathematics, and language arts.

Item Type: Instructional Unit
Level: Grades 6-9
Duration: Six Class Periods

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.

Item Type: Experiment
Level: Grades 8-12
Duration: 30-40 minutes

Activities:

This experiment gives kids a concrete way to explore Newton's Second Law of Motion by doing timed trials on a "car" built out of wooden blocks, wood screws, fishing sinkers, rubber bands, and matchsticks. They can increase the mass of the car by adding sinkers and increase the propulsion by adding rubber bands.....they will discover that the distance traveled depends on the number of rubber bands and the mass of the block.

Item Type: Experiment
Level: Grades 6-12
Duration: One class period

This wonderfully updated version of the PhET Forces simulation lets students explore force interactions, motion graphs, and friction at a broad range of levels. Choose from 5 objects of different masses, select a wood or ice surface, then "push" the object on a straight path. You can display force vectors, free body diagrams, and graphs of position, acceleration, and velocity vs. time. Record your "push" and play it back to see the sum of forces. For more advanced students: set gravitation to mimic the Moon or Jupiter and watch the effects on static and kinetic friction!

Item Type: Interactive Simulation
Level: Grades 6-12

Content Support For Teachers:

Looking for a refresher on force interactions? This four-part tutorial features multiple diagrams, illustrations, interactive problem sets, and extras for teachers. It provides a concise exploration of types of forces, how to determine net force, and how to construct free-body diagrams to represent force interactions.

Item Type: Teacher Support
Level: Grades 7-8

Assessment:

It can be difficult for beginners to recognize different force interactions, especially since these concepts sometimes run counter to the student's intuition. This interactive assessment lets them practice in a self-directed environment. They view 11 common physical situations, then decide which forces are present. Afterward, they use a pull-down menu to view correct answers -- all accompanied by explanations.

Item Type: Self-Assessment
Level: Grades 8-12
Duration: 15-20 minutes

  Applications of Newton's Laws (12)

Lesson Plans:

This is Part 1 of a two-part multimedia unit on systems, approached from the framework of simple machines.  It was developed to address the misconception of a machine as a collection of separate things. Instead, it presents the simple machine as a system to reinforce the concept of interaction.

Item Type: Lesson Plan
Level: Grades 3-5
Duration: 1-2 Class Periods

This blended learning activity is highly recommended to help kids form deep understanding of the forces that act on a spring with mass attached. It combines a lab with a PhET simulation. Students identify the research question, make predictions, conduct a fair test, then compare their lab results to the simulation. With the sim, they can explore kinetic/potential energy transformation and "transport" their springs to different planets with varied gravitational constants. (Contains content support, student guides, & assessment/answer key.)

Item Type: Lesson Plan
Level: Grades 5-8
Duration: Two Class Periods

A lesson for exploring the physics & engineering of artificial heart valves. Students examine and operate both a ball valve and a gate valve, then they work as a team of "engineers" to develop and sketch enhancements to the mechanical heart valve. Great activity for integrating engineering design in the secondary classroom.

Item Type: Lesson Plan
Level: Grades 8-12
Duration: Two Class Periods

Kids explore civil engineering and architecture as they design and build a small dome frame that can withstand a load of 120 grams on top without collapsing. Editor's Note: For a great 3-day unit that brings in concepts of compression and tension, blend this lesson with the "Teachers' Domain Forces Lab" and the PBS Building Big digital resources in Activities directly below.

Item Type: Lesson Plan
Level: Grades 5-9
Duration: 1-2 Class Periods

Activities:

This lab activity, developed by a Physics Teacher Resource Agent, gives directions for students to construct a very simple pendulum, then experiment with the mass of the bob and length of the string to see what factors affect the period of the pendulum. The printable student guide is easy to follow, yet challenges students to think deeply.

Item Type: Lesson Plan
Level: Grades 7-10
Duration: One Class Period

As students use the mouse to move objects of varying mass along a 1-D path, the simulation charts graphs of position vs. time, velocity vs. time, and acceleration.  Applied force, friction, and gravitational constants can be varied in this interactive activity. Can be adapted for use in either middle or high school.

Item Type: Interactive Simulation
Level: Grades 7-12

This activity is an animated introduction to simple machines.   Designed for Grades 3-6, it helps children gain understanding of the different types of simple machine they encounter in their kitchens, garages, bedrooms, and bathrooms. Additionally the site provides a glossary of important terms, lesson plans and a teacher's guide.

Item Type: Interactive Animation
Level: Grades 3-6

This is a collection of interactive animations that depict how forces and simple machines work together to create the compound machine.  The authors designed it for Grades 3-6 to help children understand how compound machines function and how they are different from simple machines.  It would be a good follow-up to the resource directly above -- Edheads: Simple Machines.

Item Type: Interactive Animation
Level: Grades 3-6

This four-part interactive simulation explores some of the most important forces to be considered in structural engineering. It's a fun way for kids to learn about compression, tension, torque, and shear -- and then apply this knowledge to further explore structural load. They perform virtual stretching and compression of 8 different types of building materials, then choose from rectangular, arched, and triangular shapes and test their stability.

Item Type: Interactive Simulation
Level: Grades 5-8
Duration: 30 minutes

This large collection of labs, activities, and interactive tutorials allows kids to explore large structures and what it takes to build them. They will investigate bridges, dams, tunnels, skyscrapers, and domes. The interactivity of the site is its hallmark feature, with simulation-based activities to explore forces, test the strength of materials, learn about structural load, and see how shape affects strength.

Item Type: Multimedia Collection
Level: Grades 4-12

References and Collections:

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.

Item Type: Classroom Demonstration
Level: Grades 6-12

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.

Item Type: Interactive Tutorial
Level: Grades 8-12
Duration: 20-30 minutes

  The Universal Law of Gravitation (2)

Activities:

How did scientists first directly demonstrate that the Earth rotates? This short video, seen through the eyes of a child, explores the work of French scientist Leon Foucault -- a pendulum seems to rotate as it swings, but there is no external force that would cause the rotation (clockwise in the Northern Hemisphere, counterclockwise in the Southern). Through experiments, Foucault showed that it's not the pendulum doing the rotating. It's the steady, predictable movement of the Earth's rotation.

Item Type: Video Clip
Level: Grades 3-6
Duration: 5 minutes

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 learners grasp the universal nature of gravitational attraction so that formulas make sense.

Item Type: Interactive Tutorial
Level: High School Physics

  Frictional Forces (1)

Activities:

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.

Item Type: Interactive Simulation
Level: Grades 8-12

  Rotational Dynamics (1)

Activities:

Exactly what IS centripetal force and what does it do? This short video shot from NASA's International Space Station will help students understand the center-seeking force that results in circular motion. The environment is weightless, making it easy to watch the motion without the complicating effects of gravity.

Item Type: Video Clip
Level: Grades 6-12
Duration: 5 minutes