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  • Introduction

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    Summer 2025

    Collaborators: Jack Colvin (University of Chicago Intern)

    Using Resources provided by Stevan Akerly (NSS Space Ambassadors Lead)

    Loretta Hall (NSS Space Ambassador)

    Kevin Simmons (NSS Space Ambassador & BLUECUBEAEROSPACE CEO)

    Frances Dellutri (NSS Director of Education)

    Background:

    Have you ever wondered how rockets soar so high in the air, almost as if they are powered by magic? To understand how they work, we must first understand the word "propulsion". We will start the lesson by examining what this word sounds like and how that can help us visualize what it means. Next, we will meet Sir Issac Newton and discuss how propulsion relates to Newton's 3rd Law: one of the most famous statements in all of physics. Lastly, we will end the lesson by finally connecting these ideas to rockets and create drawings of very own rocket designs! 

    Lesson Goals: 

    • Understand the word propulsion and start to get an idea of what Newton’s third law is 

    • Explore the dynamics of what happens when we push or pull on something 

    • Start to connect both of these ideas to rockets and thrust 

    Related Lessons:

    Rocket Math High School and University: https://spacedge.nss.org/course/view.php?id=330

    Rocketry Engineering High School and University:

    https://spacedge.nss.org/course/view.php?id=326 

    Rocketry:  https://spacedge.nss.org/course/view.php?id=51

    Recent Space Developments: https://spacedge.nss.org/course/view.php?id=47#section-2

    Education Standards: 

    Next Generation Science Standards (NGSS) 

    3-PS2-1, A, B, Forces and Interactions 

    Cross Cutting Concepts, Cause and Effect

    PS3.A

    3-5-ETSI-1,2,3



  • Part One: Exploring the word "Propulsion"

    Today, are going to be exploring the word propulsion, talking about what it means, why it is important, and how it connects to rockets. To start, however, we are going to ignore what it means, and just think about how it sounds and feels when we say it. Start by saying the word propulsion a couple times, either out loud or to yourself. How many syllables does it have? What action do you take with you mouth when you say the word? How does it feel? 


    Personally, when I say propulsion, I feel a couple things. First of all, I feel a strong pressure in my mouth on the first syllable. It’s like I’m holding something in. Then, when I get to the second part with the “p,” it feels like I’m pushing that pressure out of my mouth! It’s almost like a little explosion of air. I noticed that saying propulsion feels kind of violent, but in an exciting way like a blast of energy. Can you think of any other words that feel similar for you to say? Share them with others in our forum below!

  • Part Two: The Meaning of "Propulsion"

    Interestingly, a lot of the ways we described how propulsion feels when we say it are similar to its meaning! In simple terms, propulsion means the same thing as pushing. Instead of saying that we push something forwards, we can say we propel it forwards, another form of the word propulsion. Specifically, propulsion is often associated with a violent or strong push.


    • assign icon
      Drawing our own experiences with propulsion Assignment
      Opened: Wednesday, 17 September 2025, 12:00 AM

      Can you think of a time you have pushed something in the past? Draw a picture of you doing that action! What object was pushed in your example? Draw arrows on your picture to show the direction of the push, and the direction that every object (including yourself) traveled!

  • Part Three: Newton's Third Law

    Watch this video to learn more about who Issac Newton was and what a great scientist he was:

    A very famous scientist named Issac Newton spent a lot of his life studying pushes and pulls. Through his studying he came up with a very novel idea now named newton’s 3rd law that explained a lot about how pushes work. Newton’s law states that every push has a push back. In other words, when you push something, it pushes back on you. It is ok if this idea is a little bit confusing right now. We are going to explore it a lot more over the course of the lesson!

    Free image from freeimages.com, Depicting Sir Isaac Newton at work.

    Lets start to understand by talking about an example that some of you might have drawn: pushing off of a swing on a swing set. Specifically, lets think about which direction everything moves when pushing off of a swing: 

    1. Which way is your push?

    2. Which way does the swing move? 

    3. Which way do you move? 

    When pushing off a swing, you push backwards on the swing, and send the swing going backwards. However, strangely, you go forwards. Why? Well, this is an example of Newton’s third law. When you push backwards on the swing, the swing actually pushes you back, sending you forwards! 


  • Part Four: Equal and Opposite

    Some of you might still be confused by this, especially if you drew a picture of kicking a soccer ball or pushing a model train. When you kick a soccer ball, you push the ball forwards, but where is the push back? Why don’t you go flying backwards like jumping off of a swing? Lets think about it using an activity!


    Activity: Gather three balls of all different sizes and weights, maybe a tennis ball, a soccer ball, and a basketball, and give each a push with two hands as hard as you can!

    • What do you feel when pushing each ball? 

    • Do you feel anything different between any of the balls? Which ones? 

    • Do you feel a push back from any of the balls, almost like you are falling backwards a little bit from pushing it? 

    It is likely that you did not feel anything when pushing the lighter objects, but you felt pushed back when you started getting to the heavier ones. However, this isn’t because the push back doesn’t exist for the lighter objects. Instead, there is a final part of Newton’s 3rd law that we haven't talked about yet! 


    Newton’s 3rd law doesn’t just say every push gets a push back, it says that every push gets an equal push back. You don’t feel a push back when you push the lighter objects because your push was very small, so the push back is also very small. But it is still there!


    We use Newton’s 3rd law when we walk around every day - Literally! When we walk, we use our feet to push backwards on the ground, and in return, we get pushed forwards. Try this out yourself by walking around and exaggerating the push backwards on the ground. See if you can feel the ground pushing you forwards! 



  • Part Five: Propulsion and Rockets

    Does everyone remember what propulsion is? As a refresher, propulsion, or to propel, means the same thing as pushing. However, more often than not, propulsion is specifically used to describe the push that rockets used to get into the air. Rockets use the same idea that we do when jumping off of a swing to get into the air! Specifically, just like jumping off of a swing, rockets use Newton’s 3rd law by pushing something backward in order to get a “push back” to get propelled forward. Instead of a swing, however, rockets push a huge amount of air backwards in order to generate their push back. 

    An animation depciting how Newton's 3rd Law works to power rockets

    Activity: We can demonstrate this effect using just a balloon! Take a balloon, blow it up and then release it into the air: 

    • What happens to the balloon when you let go? 

    • What happens when the balloon runs out of air? 


    If you would like a more precise form of this experiment, watch the this video: Kid Science Propulsion and try it out for yourself! What do you observe? How is it similar/different to the when you tried the experiment without the string? 


    You probably observed the balloon starts to fly around wildly when you let it go! This is an example of propulsion. The balloon moves around because as it deflates, air is pushed out of it, causing the ball to move forwards! This is also why the balloon stops flying and falls down after it runs out of air: the air acts almost as the “fuel” pushing the balloon forwards. Rockets work in a very similar way!




  • Part Six: The Exhaust

    The only problem with comparing a balloon to a rocket is that a rocket is a lot, or perhaps more accurately A LOT bigger and heavier. Image a balloon as big as a rocket. It would take a HUGE amount of air to lift it off the ground. Instead of air, rockets use a hot gas to overcome gravity and launch into space, and they produce that gas by fire! Specifically, when a fire is produced, it makes a lot of heat and smoke. Think about a campfire.

    Rockets work by lighting huge fires located in a special, heat-resistant compartment called the combustion chamber. This process produces tons and tons of smoke and heat, which is where the rocket gets the thrust (push) it needs to generate the “push back” that propels it into the sky. During a rocket launch, the fire is so hot and produces so much smoke that it basically creates a mini, controlled explosion, sending the rocket careening into the sky! A rocket propulsion system like this is used to propel both airplanes in the sky and rockets into outer space.



    Image 2: NASA. (1992). STS-45 Atlantis, OV-104, lifts off from KSC Launch Complex (LC) Pad. NASA Image Gallery. Retrieved 2025, from https://images.nasa.gov/details/s45-s-055.


  • Postcards to Space!

    Send a Postcard to Space through NSS Supported Blue Origin Club For The Future initiative! Here is your opportunity to use the propulsion of a rocket to send something you create all the way up into space!

    Visit: SpacEdge Academy Postcards in Space Course