Investigating Newton's Third Law through Film Canister Cannons- Remix
Investigating Newton's Third Law through Film Canister Cannons
Summary
In this physics lab (best done outside), students will explore Newton's Third Law - 'For every action there is an equal and opposite reaction'. Students will fill empty 35-mm film canisters with water and part of an Alka-Seltzer tablet, place the cap on, and place the canister either cap side down or the cap against a hard surface like the school building. Students will measure the distance the canister is pushed away from the building or into the air. Students will summarize their understanding of Newton's Third Law and suggest applications of the Third Law in everyday life.
Learning Goals
This activity is designed for students to learn about controlling variables in an experiment, observing, and recording data. Students will also learn to analyze data after changing variables and analyzing differences. Students will also suggest applications of Newton's Third Law to everyday activities.
Context for Use
This activity is intended to demonstrate the effect of Newton's Third Law as a result of a release of chemical energy. Prime students to think about Newton's third law by watching and discussing the video linked below before begining the activity.
Newton's Laws in Space Video Link
This activity is best done outside due to the liquid that will be expelled by the canisters.
Subject: Physics:Classical Mechanics
Resource Type: Activities:Lab Activity
Grade Level: Middle (6-8)
Description and Teaching Materials
Students will discuss the order of operation and the data to be gathered. Students will fill an empty film canister with 0.5 cm of water. Start with placing 1/4 piece of an Alka-Seltzer tablet into the canister, replace the cover, and then quickly place the cover end up against a building or cap-side down on the ground. Denture cleaning tablets can also be used and are often a more affordable option at about half the proce of alkaseltzer. After the explosion, measure how far the canister was pushed from the building or observe how high up the canister was pushed. After several trials, try 1/2 of a tablet. Record results on the data sheet. Gather students and review results. Discuss results in relation to "For every action there is an equal and opposite reaction." Ask for other applications of Newton's Third Law. 35 mm film canisters often have to be special-ordered as this is not a common household item anymore. One possible source is linked here: https://www.teachersource.com/product/rocket-film-canisters/air-pressure-rockets
Teaching Notes and Tips
Students should wear safety goggles to prevent getting hit in the eye by a film canister or by a splash of Alka-Seltzer. If they should be splashed, rinse the eye and seek medical attention if pain persists.
Two objectives that will relate directly to Newton's Third Law are:
1) Different amounts of Alka-Seltzer/denture cleaner
2) Changing the mass of the canister by adding a mass like a fishing sinker to the canister
To gain the most information about Newton's Third Law, it will be beneficial to have some groups of students test each of the variables.
It is imperative to have students identify the variable they will test before starting experimentation. In order to make sure that you have a few groups testing earch variable. You can allow students to choose or randomly assign a variable to groups.
Have students identify the variables in their experiment, plan the investigation, and design their data tables before going outside.
| Variable Type | |
| Independent Variable | |
| Dependent Variable | |
| Controlled Variables (at least three) |
|
Hypothesis:
Procedure:
| Independent Variable : | Distance Trial 1 | Distance: Trial 2 | Ditstance: Trial 3 | Average distance |
Students will work in groups and fill out data sheets comparing the amount of Alka-Seltzer or denture cleaner and the distance the canister was pushed away from the building or up from the ground.
Assessment
Have students graph their data and explain what they saw in the context of Newton's Third Law.
Have students draw a diagram of the action/reaction forces on the rocket.
Have students list three other instances/applications of Newton's Third Law of Motion.
References and Resources
How and Why Did you Remix this Resource?
The original resource included many variables that students could test. However, I narrowed the variables to include the mass of the canister or the amount of propellant in the canister. By narrowing down the number of variables, it ensures that students are focused on Newton's third law, as opposed to other concepts. Because film cannisters are not a household item, I included one possible resource for this material. To help students stay on track, I included a student activity sheet that will help students identify variables and record their data. Finally, I have included ideas for assessing student understanding.