# Force and Motion: Newton's Third Law

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Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Force and Motion SciPack. It provides a conceptual and real-world understanding of Newton’s Third Law of Motion, addressing common misconceptions associated with this law. Whenever one object exerts a force on another, an equal amount of force is exerted back on it. These equal and opposite forces are exerted simultaneously on the objects involved.

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Reviews (34)
• on Sun Oct 22, 2017 6:58 PM

Great resource that helped me, help my students! Gave great ideas on activities to show my students!

Patricia W

• on Sat Mar 07, 2015 6:51 AM

....an opposite reaction. Students will love to apply this law in playing pool and using balloon cars!

Robin Willig (Rye Brook, NY)

• on Tue Sep 02, 2014 7:26 AM

I really enjoy Science Objects. In 1-3 hours, the Force and Motion: Newton's Third Law Science Object will help me re-learn, refresh, or learn for the first time some critical science concepts I will have to know to obtain my Science Educator credentials. I appreciate that I can complete them at my own pace, and that, if used as park of a SciPack, I have access to a content expert to go to for help. The NSTA Learning Center Science Objects are very beneficial!

Naomi Beverly (Marietta, GA)

• on Sun Feb 23, 2014 12:55 AM

Newton's third law is explained very explicitly.The matter engages the reader into inquiry. One continues to remain interested until the lesson is finished.The problems given are relevant.It is useful for students,teachers and teacher educator as well.Another good point is including preconcepts of learners.Worth reading !

Shashi Prabha

• on Tue Aug 06, 2013 9:11 AM

This resource provided a large amount of useful information and simulations that helped me better understand Newton's Third Law. I was able to use this to recall things I learned many years ago. I highly recommend this to anyone who needs a refresher course on force and motion.

Stephen

• on Wed Apr 28, 2010 8:36 PM

I was more familiar with this law because of what I learned in PISA workshops. Also used similar demonstrations in class to help clarify the students understanding. Gave this one a five star rating.

Jean O (Jersey City, NJ)

• on Sun Apr 25, 2010 4:26 PM

The 3rd law says that for every action (force) there is an equal and opposite reaction(force). Forces are found in pairs. This law I found to be the most interesting. Upon further research after watching the video,I found some other examples that I feel would work well in a classroom setting. #1 Sitting in a chair. Your body exerts a force downward and that chair needs to exert an equal force upward or the chair will collapse. This is ideal for students who sit at their desks in the classroom! An easy concept for them to grasp. #2 Shooting a cannonball. When the cannonball is fired through the air(by the explosion) , the cannon is pushed backward. This example works excellent when incorporating science with social studies.I also feel that Title will be a great hook to get the children excited about learning all 3 of Newton's Laws.

kathleen temple (hoboken, NJ)

• on Tue Apr 20, 2010 8:52 AM

This was an excellent explanation of Newton's Third Law. The simulation of the ice and snowball can be used in my fourth grade classroom with very little confusion associated with it. I especially liked the initial "experiment" of pushing on your palm. This is a great introduction to the third law that can be translated to any classroom.I can use this explanation the next time I teach force and motion .

Debra Czerwienski (Bayonne, NJ)

• on Wed Mar 24, 2010 3:45 PM

Many practical applications of this law were extensively explored in this article. These will be very helpful for the teacher as well as for the students to understand the concept.Close observation is necessary to be able to apply the concept since this happens every moment of their life.

Ida Barrera

• on Tue Mar 16, 2010 2:33 PM

I am an inclusion teacher and the best way to explain Newton's Third Law according to me is "If you push something it will push back".

Antoinette M

• on Tue Mar 16, 2010 2:21 PM

This tutorial was a bit easier to follow than the second. Newton's Third Law might be easier to teach to third graders than the second law although some of the concepts will not be easy to get through to them. I liked a lot of the activities that I can do to show them that for every action, there is an equal and opposite reaction. They would definitely have the misconceptions about the more mass of an object, the amount of force exerted on another object, and the reactions. Doing the actual physical activities to explain this law would be fun for them but also help with the explanation of the concept. It surely did for me!

Nancy Mielnicki

• on Tue Mar 16, 2010 2:20 PM

Like the previous tutorials, I found this one to be very informative and helpful. Newton's 3rd Law, “for every action there is an equal and opposite reaction” gives students the misconception that "reaction" is just a sequence in which one force leads to the other and that word “opposite” applied to that reaction acts on the same object. The third law in simple terms is, "anytime one object is exerting a force on a second object, the second object is exerting a force on the first that is equal in size and acts in the opposite direction". Getting that across is the challenge. The interactive simulations help support and show that explanation on the third law. I find that doing a lot of hands-on and interactive activities in my class help them understand the lesson a lot better. I will definitely be using this tutorial, and the other tutorials as well, in my future lesson plans.

Maria Palanca

• on Tue Mar 16, 2010 2:14 PM

One part of the lesson I found confusing. I understand that walking or crawling on ice is difficult because ice has no friction, but I did not understand the objective. Otherwise, I am capable of sharing the push and push back with the students.

Priscilla Jones

• on Tue Mar 16, 2010 1:41 PM

“Force and Motion: Newton’s Third Law” is a helpful “refresher” of Newton’s Third Law. I agree with the common misconception section that states that many students, especially at the third grade level, believe that if an object is at rest, no forces are acting on it. The comparison of the spring mattress to the atoms in an object (pushing back on you) will hopefully help clarify this misconception. Because these concepts are difficult to demonstrate, I feel that many of my students will be left with questions. Once again, the questions that were sprinkled throughout the tutorial were extremely helpful.

Dina M (Weehawken, NJ)

• on Tue Mar 16, 2010 1:19 PM

For every action there is and equal and opposite re-action. This article was a nice break down of this concept and provided excellent animations for my students to see on my projector. With my students outside, I put vinegar in a film canister, covered it with the lid that has an Alka-Seltzer glued to it. The canister flies off in one direction and the lid takes off in the opposite direction. This helps the students see first-hand Newton’s Third Law of Motion.

Vanessa

• on Tue Mar 16, 2010 11:36 AM

This tutorial was a little more difficult than the previous two. The questions were also more challenging. The balloon rocket activity is an easy and accessible hands-on way to demonstrate force in the classroom. For every action there is an equal and opposite reaction can be related to students using simple class objects; such as, desks and chairs. The PISA marble activity would be another way to demonstrate the Third Law in the classroom. Atoms and electromagnetic forces act like springs and push back on you. This tutorial was very helpful in understanding motion.

Maryanne (Bayonne, NJ)

• on Sat Mar 13, 2010 6:38 PM

Well maybe I didn't know all I should have known about Newton's Third Law. The idea that equal forces were being exerted simultaneously was not as enforced to my students and it should have been. Also the idea of pressing your finger, and the table edge to demonstrate that objects push back is one I will use from now on. It is wonderful to have these visual demonstrations so my students can see and experience the "Laws" firsthand.

Barbara Henderson (Jersey City, NJ)

• on Sun Feb 28, 2010 3:27 PM

I had some prior knoledge but I had a misconception that the greater the inertia between two objects pushing against each other the greater the force would be in one direction, I know now that it would be an equal reaction. Also, the concept of two objects both pushing back against each other are equal.I would implement the clearer explanation of this third law, I can understand how my students would expect all objects to have an equal yet opposite reaction.

Bess M

• on Sat Feb 20, 2010 3:12 PM

The tone of this tutorial is very friendly. It appears easy to grasp the meaning of Newton's third law. To explain force on inanimate objects using electromagnetic forces among atoms in the object is a very good idea. It gives an effective correlation between the past lesson on the nature of matter and on the new lesson on force. This makes clear the action-reaction part of Newton's third law.For the fourth grade, I rather use the action-reaction concept and let them deduce that these exerted forces must be exerted simultaneously. The theory on the exerted forces being equal is hard to teach. The mathematical explanations and the assumptions are not obviously understood. I hope the students will just take my word for it.

Isabel Ramos (1601 Central ave. Union City, NJ)

• on Sat Aug 08, 2009 7:06 AM

Will absolutely recommend these to colleagues for professional development. Elementary teachers always seem to be light on science background. These are small enough chunks of information, w/o time pressure, and free. Perfect.

Liz M (Interlaken, NY)

• on Sun Nov 26, 2017 2:13 PM

Before using this tutorial, I personally had a good understanding of Newton's Laws. After using it, it provided me with more thorough, valuable information. I would think that it would be useful to the students. It provided great hands-on activities for them to keep them engaged. The only problem I have with it is the mathematical concept of the law.

Michael Moran (Medina, OH)

• on Fri Apr 30, 2010 9:51 PM

It was difficult to rationalize how an object could push back on you. But the comparison to springs in a bed on a microscopic level really helped me get it. I never thought that the net force by one object will cause an equal but opposite force back by the object it hits.

Judith V

• on Thu Apr 29, 2010 5:42 PM

I found the frozen pond demonstration amazing! In a frictionless environment, I would have thought walking forward would be the solution to moving to the other side. I was shocked that throwing the snowball forward would propel a person backwards. Having read about this 3rd law, that object A (throwing the ball forward) exerted that same amount of force on the person pushing him backwards I now understand the concept. This coupled with the simulation of the 18-wheeler hitting the compact car I think will need more examples to convince my students that the force exerted is equal with both objects. And I will also have to be able to "drive the notion home" that the forces are exerted simultaneously rather than one being a reaction of the other. Regardless, I feel these activities will enhance my students knowledge on the idea of "action and reaction" or "force and motion" as described in Newton’s 3rd Law. The videos are short, but to the point, and I plan using them as a learning tool with my classroom prior to NJ ASK.

Denise H (Piscataway, NJ)

• on Sun Apr 11, 2010 8:40 AM

Overall, I thought this resource was very helpful. Some of the activities I even tried with my students. Opening with imagery will definitely get the students engaged and the interactives will help students to understand friction and how it applies to this law. Once the students completed the exercises, they were asked several questions about what they witnessed and then given several activities that could be easily completed inside the classroom and would help students to recognize what Newton’s Third is all about. I didn’t really care for the Air cart simulation, because I thought it was a little hard for fifth grade students to understand, but the explanation after was helpful. The balloon experiment especially made it easier for my students to understand how equal and unequal forces act on objects.

Jacqueline Docampo

• on Sat Apr 03, 2010 8:15 AM

The video clips for Newton’s 3rd law are very helpful in understanding exerted forces; especially video clip “Action and Reaction”. The self-checking questions are useful throughout the reading to make sure you have a clear understanding of the law. This resource also has a glossary page with vocabulary words that are used for the explanation of Newton’s third Law.

Marilyn Ortiz (Jersey City, NJ)

• on Sun Mar 21, 2010 6:20 PM

Newton's Third Law can be confusing to students as they interpret action reaction as cause and effect. This concept can be easier to grasp with the help of the animations and explanations. I felt the summary was important, and liked the fact that it suggested lesson plans and on-line resources.

Natalie V

• on Tue Mar 16, 2010 1:32 PM

The article was easy to understand and the activities were helpful. To introduce this law we discussed how rockets work and I utilized the computer lab once again for student-friendly reading and activities related to this law. Afterward, as our lab activity I distributed film canisters which had an Alka Seltzer tab glued to the inside lid. The students filled their canister with vinegar and inverted the canisters outside to observe the results. The students observed that for every force there is a reaction force that is equal in size, but opposite in direction.

Wingert

• on Tue Mar 16, 2010 11:28 AM

Wow! That was a lot of information! The 3rd law is definitely more complex than the first two. I thank the author for the interactive simulations because they definitely put me at ease. I still have many misconceptions similar to the ones that were listed to the in the tutorial. The author did use simple terms, but I am not completely grasping the concept. I think that I will have to re-read the tutorial for a better understanding. I do not feel confident with the information yet!

Vanessa Geerin (, )

• on Tue Mar 16, 2010 11:19 AM

The information presented in the article, Force and Motion: Newton's Third Law was very thorough. Everything you wanted to know about the science theory is presented with easy to read informational text and pop up simulations. One aspect of the article that is helpful is the subheading: common misconceptions. In particular, the author advises rephrasing of the words in the third law to emphasize that the forces applied are equal. The examples provided helped further explain the concept.

kathleen jorgensen (, )

• on Sun Mar 07, 2010 3:34 PM

This tutorial was more comprehensive than the 2nd newton's law tutorial. However, I do feel that some of the answers to the multiple choice questions were misleading. Upon what a person knows from personal, previous experiences and what the actual correct answers are differ. For example, the question that regards two children shoving eachother, a normal reaction would be to say the child that falls to the ground experiences a greater force than the other. However, this is not true...they both experience the same equal and opposite force. I am still somewhat confused on how this is. I do understand and can recall the concepts, but confusion of applying them is still a concern. I do wish that there was more interactive activities with this tutorial than all of the text reading as most people learn from doing.

nicole q (jersey city, NJ)

• on Thu Apr 29, 2010 7:16 PM

The part of the tutorial that I thought was most helpful was the analogy of atoms to mattress springs. Teaching Newton’s Third Law, I think students would question how objects such as a floor or table could “push back” when they aren’t living things. They do understand that objects and matter are made up of atoms, so being able to compare atoms inside of an object pushing to springs inside of a mattress pushing will be helpful. Many times you can feel or see the springs moving inside of a mattress, but there are firm mattresses where you don’t feel any movement; however, everyone still knows that there are springs inside. That is how I will try to explain how inanimate objects push back against objects. I am still confused with the concept of different forces acting on each other, which will cause acceleration (the donkey pulling the cart analogy).

kelly (hoboken, NJ)

• on Wed Apr 28, 2010 12:31 AM

I enjoyed the hands on activity using your hands/table. There were no materials necessary which allowed all students to participate & understand part of the 3rd law that...whenever you push on something, it pushes back on you i.e. When object A exerts a force on object B, object B exerts a force back on object A. The experiment between pushing on a mattress vs. a table was also a good example as it beautifully shows Newton's 3rd Law that whenever one object exerts force on another, a force equal in magnitude and opposite in direction is exerted on the first object. This will help the students to dismiss the idea that if an object is at rest, no forces are acting on the object.

Jennifer M (Bayonne, NJ)

• on Sun Apr 25, 2010 9:38 PM

I still do not feel completely comfortable with my knowledge and understanding of Newton's third law of motion. Unfortantely, I don't have a better understanding of the Mathematical concept F=ma. This part of the Science lesson was not easy to follow and I am not certain how to find the accelerated speed of an object. The hands on examples,and the illustrations/diagrams were a great help for me. This helped me to understand/accept Newton's third law "When object A exerts a force on object B, object B exerts an equal and opposite force backon on object A,regardless of the mass or motion of either object".

Gina Venable

• on Thu Apr 29, 2010 4:38 PM

Before reading this tutorial I thought I had a pretty good understanding of Newton’s third law. I felt that the reading took a concept relatively easy to understand and made it seem much more complicated. I did not enjoy the simulators as much as I did for the first and second law. Overall, I can say that Newton’s third law states that everything moves relative to everything else. If you push someone they move, and you would move as well. The force from pushing someone or something pushes you to move also. That would be the idea of equal and opposite reaction. I guess an easy demonstration to do with the students is the demo using the hands where one hand is open and the index finger of the other hand is pressing down. The students will see the indentation and notice that their other hand is pushing as well.

veronica ramos (Hoboken, )

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