4) Elastic Launcher Challenge

🏎 Elastic Launcher Challenge – Catapult STEM Project 🧸

This fun project involves building a simple catapult or elastic launcher to explore how stored Elastic Potential Energy (EPE) is converted into Kinetic Energy (KE). You will analyze factors like the launch angle and the pull-back distance to maximize projectile range or accuracy.

The project is divided into two main phases: Quarter 1 for Design & Trifold Preparation and Quarter 2 for Building & Testing your model.

💡 Phase 1: Concept & Design & Trifold Preparation (Quarter 1)

This critical phase involves defining the entire experiment, documenting the design plan, and preparing all non-data sections of your trifold display. You must prepare sections 1 through 5 below for your Quarter 1 deadline.

1. Hypothesis and Research Question

How does the amount of energy stored in the elastic material (EPE) affect the distance the projectile travels?

Research Question: “How does the pull-back angle or distance of the catapult arm affect the flight range of the projectile?”
Hypothesis: If we increase the pull-back distance of the catapult arm, then the projectile will travel a greater distance because the elastic material stores a larger amount of elastic potential energy, which converts to more kinetic energy upon release.

2. Materials and Variables

List all items needed for the build and identify the elements that will be controlled or measured.

Materials You'll Need

Popsicle sticks, dowels, or cardboard (catapult base/arm)
Rubber bands or elastic string (the launching mechanism)
Tape and glue
Small projectile (e.g., pom-pom, plastic bead, small marshmallow)
Plastic bottle cap or small spoon (projectile holder on the arm)
Cardboard base to mount the catapult (optional but recommended)
Measuring tools (protractor for angle, tape measure for distance, ruler)
Marker or pen for labeling pull-back distances

Variables

Independent Variable: Pull-back distance or launch angle of the arm
Dependent Variable: Horizontal distance (range) the projectile travels
Constants: Projectile mass, elastic material type, catapult base mass, launch height, same testing surface.

3. Procedures (Design & Documentation)

Your Quarter 1 procedure focuses on the trifold content. The actual building steps are performed in Quarter 2.

Write your project title: “Elastic Launcher Challenge – Catapult”.
State your research question and hypothesis.
Draw a labeled diagram of your catapult design, clearly indicating the pull-back distance and the launch angle.
Explain in a short paragraph the energy conversion process from Elastic Potential Energy (EPE) to Kinetic Energy (KE).

4. Expected Results

Based on your research and knowledge of physics, what do you expect to happen?

You should find that increasing the pull-back distance increases the range (up to a point). Additionally, the projectile launched closest to a 45-degree angle should achieve the maximum horizontal distance, as this angle provides the optimal balance between initial velocity and hang time.

5. Expected Conclusion (Pre-analysis)

How will your results theoretically support your hypothesis?

The experiment should support the hypothesis, confirming that the distance traveled is directly related to the stored EPE and the launch angle. The optimal launch angle of 45° demonstrates principles of projectile motion where horizontal and vertical velocity components are balanced for maximum range.

🛠 Phase 2: Working Model (Quarter 2)

In this phase, you will execute the plan you designed in Quarter 1 by building the elastic launcher and collecting real data.

Construction and Testing Procedures

Prepare the base: Stack 6–8 popsicle sticks directly on top of each other and tightly wrap a rubber band around each end to form a solid base bundle.
Create the launcher arm: Take a single popsicle stick and glue or tape a plastic bottle cap (or small spoon) to one end. This will hold the projectile. Allow glue to dry before testing.
Attach the arm to the base: Slide the launcher stick through the middle of the base stack so that it crosses the bundle near one end. Use a rubber band wrapped in an “X” pattern around the center of the base and launcher arm to act as the pivot point (fulcrum). The cap end of the arm should be free to move up and down.
Stabilize the launcher: Use tape or glue to fix the base bundle onto a piece of cardboard or directly onto the table so the catapult does not slide when you launch.
Mark pull-back distances: Place a ruler or strip of paper along the side of the launcher arm. Mark at least three pull-back distances (for example: 2 cm, 4 cm, and 6 cm) and label them as Short, Medium, and Long.
Set a fixed launch angle: Use a protractor or a pre-drawn cardboard angle guide to keep the launch angle approximately the same (for example, 45°) each time you pull back the arm to a mark.
Test pull-back distance: Place the projectile in the cap, pull the arm back to the Short mark at the chosen angle, and launch. Measure the horizontal distance from the front of the base to where the projectile first lands. Record the value in a data table.
Repeat for accuracy: Perform at least three trials for each pull-back distance (Short, Medium, Long). Keep the projectile type, launch surface, and angle the same.
Optional – Test launch angles: Choose one pull-back distance (for example, Medium) and test different angles such as 30°, 45°, and 60°, keeping everything else constant. Record all distances.
Analyze your data: Calculate the average (mean) distance for each pull-back setting. Draw graphs such as Range vs. Pull-back Distance and, if you did the optional test, Range vs. Launch Angle. Use these graphs to help you write your final results and conclusion on the trifold.

📜 Trifold Display Board Instructions

Your final project will be presented on a standard trifold display board (approx. 37 inches high and 48 inches wide when fully open).

Board Size & Suggested Layout

Organize your board to be easy to read from left to right and top to bottom.

Panel	Suggested Content
Top Center	Project Title (Big and Bold)
Left Panel	Question / Problem, Background / Introduction, Hypothesis
Center Panel	Materials, Procedures (steps), Photos / Diagrams, Graphs / Tables (your data)
Right Panel	Results (what happened), Conclusion, Reflection / What you learned

Design Tips for a Professional Look

Title: Use a short, clear title that can be read from across the room.
Clarity: Print all text on white or light-colored paper.
Font Size Guidelines:
- Title: 72 pt or bigger
- Headings: 32–48 pt
- Body text: 18–24 pt
Aesthetics: Keep it neat—align boxes, use rulers, and avoid crowded text. Use 2–3 matching colors for borders and headings.
Visuals: Add photos, labeled diagrams, and charts (your data) to make the board engaging.

🎬 Helpful Videos

Catapult Building Guide (Popsicle Stick Launcher)

Watch this step-by-step guide to build a stable popsicle-stick catapult similar to the launcher used in this project.

Trifold Design Tutorial

Tip: Plan your layout on scrap paper first, then print, cut, and finally glue everything onto the board.

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