Lesson Plan

Newton's Laws Part 2 - Newton's 3rd Law

Subject Area

Science

Grade(s)

8

Overview

As the second installment of a series of lessons on Newton's 3 Laws of Motion, this lesson focuses on Newton's Third Law. Students will take part in an activity exploring the motion of colliding objects. Students will photograph these collisions as a demonstration and explain how Newton's 3rd Law and balanced & unbalanced forces relate to their collision.

This lesson results from a collaboration of the Alabama State Department of Education and ASTA.

Science (2015) Grade(s): 8

SC15.8.10

Use Newton’s third law to design a model to demonstrate and explain the resulting motion of two colliding objects (e.g., two cars bumping into each other, a hammer hitting a nail).*

Unpacked Content

UP:SC15.8.10

Vocabulary

  • Sir Isaac Newton
  • Newton's Third Law of
  • Motion
  • Force
  • Model
  • Mass
  • Speed
  • Velocity
  • Action
  • Reaction

Knowledge

Students know:
  • Whenever two objects interact with each other, they exert forces upon each other.
  • These forces are called action and reaction forces; forces always come in pairs.
  • For every action, there is an equal and opposite reaction.
  • The size of the force on the first object equals the size of the force on the second object.
  • The direction of the force on the first object is opposite to the direction of the force on the second object.
  • The momentum of an object increases if either the mass or the speed of the object increases or if both increases.
  • The momentum of an object decreases if either the mass or the speed of the object decreases or if both decrease.

Skills

Students are able to:
  • Develop a model that demonstrates Newton's third law and identify the relevant components.
  • Describe the relationships between components of the model.
  • Use observations from the model to provide causal accounts for events and make predictions for events by constructing explanations.

Understanding

Students understand that:
  • Newton's Third Law states that for any pair of interacting objects, the force exerted by the first object on the second object is equal in strength to the force that the second object exerts on the first, but in the opposite direction.

Scientific and Engineering Practices

Developing and Using Models

Crosscutting Concepts

Systems and System Models

Primary Learning Objectives

Learning Target:

I will use the partner balance challenge to demonstrate and explain the action-reaction sequence of two objects colliding.

Procedures/Activities

Before/Engage:

Begin by showing the following video as a refresher of how Newton's 3rd Law applies to colliding objects: Physics of Football - Newton's Third Law of Motion

During/Explore/Explain:

Students will demonstrate the reactions of colliding forces by playing the balance challenge game in groups. The game is played by standing

Students will demonstrate the reactions of colliding forces by playing the balance challenge game in groups. The game is played by standing

The game is played by standing facing your partner about two feet apart (your fingertips should reach your opponents chest). Your hands must always remain upright with palms facing out and you may only touch your opponent on their hands. The object of the game is to push your opponent off balance or to move your hands back so that your opponent will fall off balance. Allow students to play a few rounds in groups. Follow this exploration with group discussion questions such as:

The object of the game is to push your opponent off balance or to move your hands back so that your opponent will fall off balance. Allow students to play a few rounds in groups. Follow this exploration with group discussion questions such as:

Allow students to play a few rounds in groups. Follow this exploration with group discussion questions such as:

A) What are two ways to create an unbalanced force in this game?

B) How does Newton's 3rd Law or action-reaction pairs relate to what you're doing now?

After a brief discussion, have your students take a photograph of a picture of both a balanced collision and an unbalanced collision. Have them label and explain how each of these collisions demonstrate action-reaction pairs.  Examples are provided in the attachment area.

After/Elaboration:

Once the activity is complete, have students write a reflection in their journal (or notebook) on the following topics:

1) When two objects collide, what forces determine how the objects will move?

2) What is one thing that you learned or surprised you about objects colliding?

3) What is one question you still have about Newton's 3rd Law or colliding objects?


Before/Engage:

Begin by showing the following video as a refresher of how Newton's 3rd Law applies to colliding objects: Physics of Football - Newton's Third Law of Motion

During/Explore/Explain:

Students will demonstrate the reactions of colliding forces by playing the balance challenge game in groups. The game is played by standing

Students will demonstrate the reactions of colliding forces by playing the balance challenge game in groups. The game is played by standing

The game is played by standing facing your partner about two feet apart (your fingertips should reach your opponents chest). Your hands must always remain upright with palms facing out and you may only touch your opponent on their hands. The object of the game is to push your opponent off balance or to move your hands back so that your opponent will fall off balance. Allow students to play a few rounds in groups. Follow this exploration with group discussion questions such as:

The object of the game is to push your opponent off balance or to move your hands back so that your opponent will fall off balance. Allow students to play a few rounds in groups. Follow this exploration with group discussion questions such as:

Allow students to play a few rounds in groups. Follow this exploration with group discussion questions such as:

A) What are two ways to create an unbalanced force in this game?

B) How does Newton's 3rd Law or action-reaction pairs relate to what you're doing now?

After a brief discussion, have your students take a photograph of a picture of both a balanced collision and an unbalanced collision. Have them label and explain how each of these collisions demonstrate action-reaction pairs.  Examples are provided in the attachment area.

After/Elaboration:

Once the activity is complete, have students write a reflection in their journal (or notebook) on the following topics:

1) When two objects collide, what forces determine how the objects will move?

2) What is one thing that you learned or surprised you about objects colliding?

3) What is one question you still have about Newton's 3rd Law or colliding objects?

Assessment Strategies

Evaluation: 

The class discussion, labeled photograph, and reflective journal are all forms of formative assessments to determine if students can explain the action-reaction sequence of two objects colliding.

Acceleration

A) Students can photograph & explain collisions using additional objects or props.

B) Just for fun - Students can compete in a class tournament to find the winner of the balance challenge game.

C) For an additional activity on Newton's 3rd Law that students can participate in or simply observe, view this video: https://youtu.be/5eirTBW0rpI

Intervention

Assign peer partners or other good helpers in groups with students who need remediation.

 

Approximate Duration

Total Duration

31 to 60 Minutes

Background and Preparation

Background/Preparation

Students should have a general understanding of Newton's 3rd Law and the differences in balanced & unbalanced forces.

 

Materials and Resources

Materials and Resources

A safe environment with space for students to actively move.

Technology Resources Needed

Laptop, tablet/iPad, or smartphone to record an image and edit and label the photograph.

Ability to show online videos in the classroom.

Physics of Football - Newton's Third Law of Motion

Approved Date

2016-04-28
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