# Investigating Newton's 3rd Law: Coin Flick

#### Summary

In this elementary physics investigation, students explore Newton's 3rd Law of Motion: To every action there is an equal & opposite reaction. Pairs of students will line up 5 pennies, (touching each other), between 2 rulers. The row of pennies should be an inch from one end of the rulers. They will place a 6th penny on the other end between the rulers & flick it at the 5 coins. Students will repeat the activity several times. They will draw a diagram of their observations. Students will repeat the process, flicking 2 coins, then 3 coins at the row of 5 coins & drawing what they observe. Students will summarize their understanding of the 3rd law of motion & think of another evidence and/or application of the law in their everyday lives.

## Learning Goals

Goals of this activity: have students determine a useful definition for Newton's 3rd Law of Motion through observation. Skills included in the process would be controlling variables in an experiment, observing & recording data, analyzing data & applying new learning to daily experience.

Key concepts to discover: When a force is exerted an an object, the force of the reaction is equal to the force exerted upon it. This is a universal law of nature that can be evidenced & used to advantage.

Key vocabulary words: action, reaction, exert force, variable

Key concepts to discover: When a force is exerted an an object, the force of the reaction is equal to the force exerted upon it. This is a universal law of nature that can be evidenced & used to advantage.

Key vocabulary words: action, reaction, exert force, variable

## Context for Use

This activity is intended for early exploration of the laws of motion in a 5th grade class with student pairs or small groups. Prior to the lesson, students should be familiar with the term 'variable' as it applies to an experiment. Lesson time is 30-45 minutes.

**Subject**: Physics:Classical Mechanics:Newton's Third Law

**Resource Type**: Activities:Lab Activity, Classroom Activity

**Grade Level**: Intermediate (3-5)

## Description and Teaching Materials

Materials needed per student pair: 2 rulers, 6 pennies, tape, science log books

Students arrange the 2 rulers on the table top with the line of 5 pennies between them, all touching & 1 inch from one end. Secure the rulers to the table with tape. They will place a 6th penny on the other end between the rulers & flick it at the 5 coins. The whole group of coins will move a little, but the end coin will fly off. Students will repeat the activity several times. This phenomenon is explained by Newton's Third Law of motion which states that to every action there must be a reaction. When you flick the coin, it hits the first one (the action) and that coin then tries to move away from the first one (the reaction). But it can't move because it is prevented from doing so by the next coin in the line. So, the force of the impact is passed on to the next coin until it gets to the end of the line. At this point there is nothing preventing the last coin from moving, so it flies off. Students will draw a diagram of their observations. Students will repeat the process, flicking 2 coins, then 3 coins at the row of 5 coins & drawing what they observe. The number of coins that are flicked into the row of coins will be the same as the number of coins that fly off. Students will summarize their understanding of the 3rd law of motion in their science log books & think of another evidence and/or application of the law in their everyday lives.

Students arrange the 2 rulers on the table top with the line of 5 pennies between them, all touching & 1 inch from one end. Secure the rulers to the table with tape. They will place a 6th penny on the other end between the rulers & flick it at the 5 coins. The whole group of coins will move a little, but the end coin will fly off. Students will repeat the activity several times. This phenomenon is explained by Newton's Third Law of motion which states that to every action there must be a reaction. When you flick the coin, it hits the first one (the action) and that coin then tries to move away from the first one (the reaction). But it can't move because it is prevented from doing so by the next coin in the line. So, the force of the impact is passed on to the next coin until it gets to the end of the line. At this point there is nothing preventing the last coin from moving, so it flies off. Students will draw a diagram of their observations. Students will repeat the process, flicking 2 coins, then 3 coins at the row of 5 coins & drawing what they observe. The number of coins that are flicked into the row of coins will be the same as the number of coins that fly off. Students will summarize their understanding of the 3rd law of motion in their science log books & think of another evidence and/or application of the law in their everyday lives.

## Teaching Notes and Tips

Students may want to experiment with coins of different denominations. 5th grade science is a new teaching assignment for me. I am looking for simple ideas & activities that will get students to think about the application of the laws of motion that are exhibited in their daily life.

## Assessment

Working in pairs, students collaborate in drawing a diagram of the experiment in their science log book & summarize in writing how Newton's 3rd Law of Motion affects the coins, including using the vocabulary 'force, action, impact, reaction'. Students will think of another application of Newton's 3rd Law from everyday life.

## Standards

Standard: 5.II.D.2

grade 5 strand: physical science sub-strand: motion

benchmark: 2. The student will demonstrate that the greater the force applied, the greater the change in motion.

grade 5 strand: physical science sub-strand: motion

benchmark: 2. The student will demonstrate that the greater the force applied, the greater the change in motion.