Editor selections by Topic and Unit

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

## 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:

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:

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).

Item Type: Lab
Level: 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.

Item Type: Problem-Based Learning
Level: Grades 9-12

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.

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 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.

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:

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.

Item Type: Performance Assessment
Level: 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.

Item Type: Problem Set/Homework
Level: Grades 11-12

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.

Item Type: Problem Set or Unit Test
Level: Grades 11-12

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 (10)

#### Lesson Plans:

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 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.

Item Type: Interactive Simulation
Level: Grades 8-12

This Java applet simulates an air track glider, a low-friction device commonly used to conduct experiments on Newton's Second Law and collisions. This simulation features a two-mass system connected by a string. Change the value of either mass or the coefficient of friction on the track.....and watch the effects on the motion.

Item Type: Interactive Simulation
Level: Grades 9-12

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

Free-body diagrams are a powerful tool to analyze forces exerted by interacting objects. This Shockwave-based activity gives your students self-directed practice in constructing FBD's. It's part of The Physics Classroom tutorial collection.

Item Type: Interactive simulation
Level: Grades 9-12

#### Student Tutorials:

This 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.

Item Type: Online Tutorial
Level: Grades 9-12

This four-part tutorial takes an up-close look at the meaning of forces, how we determine net force, and the use of free-body diagrams to represent force interactions. Don't miss the Gravitational Fields widget to investigate how location affects the value of the gravitational constant! Highly recommended by the editors.

Item Type: Interactive Tutorial
Level: Grades 9-12

#### 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

### Newton's Third Law (1)

#### Activities:

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).

Item Type: Laboratory
Level: Grades 11-12
Duration: Two Class Periods

### Applications of Newton's Laws (8)

#### Lesson Plans:

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 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 (1)

#### 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 (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.

Item Type: Lesson Plan
Level: Grades 9-12

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

Item Type: Interactive Simulation
Level: Grades 9-12

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

### Force Diagrams (1)

#### Student Tutorials:

This 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.

Item Type: Online Tutorial
Level: Grades 9-12
Duration: 30 minutes

### Rotational Dynamics (4)

#### Activities:

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.

Item Type: Interactive Simulation
Level: Grades 9-12

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

#### 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.

Item Type: Interactive Tutorial
Level: Grades 9-12

#### Student Tutorials:

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.

Item Type: Interactive Tutorial
Level: Grades 9-12