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3...2...1... time for water rockets!

Created: 2024-10-14

Author(s):
Jean Pierre Saghbini (UniversCiel Liban), Marc Bou Zeid (UniversCiel Liban)

Building and launching rockets is a funny activity. It combines the excitement of watching a rocket launch with the additional pleasure of mastering an engineer problem. In short, it’s fun for all ages.
In this activity students will construct their own water rockets using everyday materials and launch them, experimenting the principles of physics and engineering involved. The activity fosters critical thinking, data analysis, scientific communication skills, and even artistic skills inspiring a passion for STEAM and encouraging the next generation of scientists and engineers.
NOTE: This activity was proposed by NAEC Team Lebanon within the Sabir co-design project developed by the OAE Center Italy (Milan, 2-6 September 2024). For more information: link to OAE Center Italy webpage dedicated to the project.

Materials

In the attachements you will find:

a Teacher Handbook (pdf)
a Presentation for the teacher to be used in classroom (ppt)
a Student Worksheet to be printed out and used to record results of launches (one or more for each group) (pdf)

For each group of students building a water rocket:

Plastic bottle: Choose Fizzy drinks bottles made from PET (Polyethylene Terephthalate).
Cardboard or foam, Scissors, Tape, markers or paint
Water
Wood sticks
Tennis Ball
Air pump or bike pump equipped with barometer if possible. (one to be shared for all groups)
Cork Stopper (can be shared for all groups)
Nylon Tube (can be shared for all groups)
Fixing paste material (can be shared for all groups)

Image1: material needed for the water rockets.

Goals

Foster creativity and problem-solving: Encourage students to design and construct their rockets, considering factors like stability, aerodynamics, and flight performance
Develop teamwork and collaboration: Encourage children to work in teams, fostering communication, cooperation, and the ability to collectively solve problems.
Enhance critical thinking skills: Encourage children to analyze data, make observations, and draw conclusions from the rocket launches, promoting critical thinking and scientific reasoning.
Inspire a passion for exploration and learning: Spark curiosity and enthusiasm in children for science, engineering, and space exploration through an exciting and interactive activity.
Provide an opportunity for creativity and personal expression: Allow children to decorate and personalize their rockets, fostering their creativity and individuality.

Learning Objectives

To have direct application in a practical way of several physics laws:

Action/reaction principle (Newton's Third Law)
Projectile motion (Newton's Second Law)
Gravity

Background

How does a water rocket work?

Action-Reaction Principle (Newton's Third Law): when air is pumped into the rocket, it builds pressure inside the bottle. Releasing the air from the bottle causes a reaction as the water is forced out, propelling the rocket upward.

How does a water rocket move once it is launched?

Projectile Motion: when the rocket is launched, we will consider it will behave as a projectile with a parabolic flight path, where the only force to consider is gravity. If we apply Newton's Second Law to the rocket, we therefore find that the horizontal component of the object's velocity is constant while it is in motion and we are able to measure or calculate the parameters of its flight.

Reminder: If a projectile moves at high speed, we should consider the effects of air resistance, but most projectiles we deal with move slowly enough that we can neglect these effects (just as water rockets).

What about a water rocket launched vertically?

In this activity, the focus of the last part of the activity is on vertical launches. In this case the equation of the trajectory is simplified and we will be able easily to calculate the initial speed of the launch measuring its duration T, and then the maximum height reached in the launch.

In attachment you can find a Teacher Guide with the physics background and a ppt presentation to be used in classroom in this activity.

Full Description

1. Introduction and Preparation (orientation)

Explain the goals of the activity: Astronauts are stuck in space and they count on you. You have to prepare, as soon as possible, a space mission to save them. What will be the most important thing to prepare? A rocket. In the next three hours the life of these astronauts will depend on you finding the optimum design for a rocket to launch into space. We should find the optimum design of the rocket to reach the highest point.
Introduce the students to the concept of water rockets, highlighting the principles of physics and engineering involved. (Actions/Reaction principle and Projectile trajectory). You can use the powerpoint presentation attached.
Introduce the formulas that will allow students to calculate the maximum height reached by the rocket and its initial speed in the last part of the activity (optional).
Explain to the students that the same principles that apply to water rockets also apply to real space rockets.
Also: underline the importance of teamwork, creativity, and safety.

2. Rocket Construction (conceptualization and Investigation)

Divide the students into teams and distribute the materials (plastic bottles, cardboard or foam, scissors, tape, markers or paint, an air pump or bike pump, water).
Instruct each team to design and construct their water rocket. They can start by decorating the plastic bottle with markers or paint to personalize their rockets.
Attach the tennis ball to the bottom end of the bottle using tape to make the cone and add some weight to the top of the rocket.
Cut out triangular-shaped fins from cardboard or foam using scissors. The number of fins can vary, in order to find the optimum number for better stability.
Attach the fins to the top end of the bottle (the bottom of the rocket) using tape, ensuring they are evenly spaced and securely attached. The fins help stabilize the rocket during flight.
Attach the wood sticks at the top end of the bottle (the bottom of the rocket) using tape, ensuring high support for the rocket (a rocket launchpad)
Make a hole in the cork stopper and pass the nylon tube through it. Put fixing paste material all around the tube to prevent any air leakage. The level of the tube passing the hole should be higher than the water level in the bottle if you are using a manual air pump. If it is an electric air pump, the level of the tube can be lower than the water level. which will allow the students to watch air passing through the water (air bubbles forming during launch time) (refer to the attached videos)
Encourage creativity and problem-solving as the teams experiment with different fin shapes, sizes, and positions to optimize rocket performance.

Image 2: rocket construction. Credits: UniversCiel

3. Pre-Launch Preparation

Set up a launch area free from any obstacles or obstructions.
ATTENTION: explain carefully the importance of safety and safety distances, especially for the landing of the water rocket (minimum 3m for the students away from launching points to a maximum distance of a 30m diameter to ensure a place for landing).
Fill the rocket's bottle partially with water, leaving some air space at the top. The exact amount of water can vary and the students have to find the optimum filling factor to use.
Attach the pressurization mechanism (such as an air pump or bike pump) to the rocket's cap, ensuring a tight seal. Be aware that the tight pressure will vary and will also have an impact on the initial pressure and velocity affecting the maximum height reach.

Image 3: water rocket setup. Credits: www.careersportal.co.za

4. Experiment launching at different angles

Gather all the teams in the designated launch area, maintaining a safe distance from the launching point.
One team at a time will launch its designed rocket.
With adult supervision, carefully pressurize the rocket by pumping air into the bottle until the desired pressure is reached. The pressure builds up as the air compresses the remaining air and the water inside the bottle.
Start a countdown to build excitement. (3...2..1...GOOOOO)
Observe the rocket's takeoff as the pressurized air forces the water out through the bottle's opening, generating thrust and propelling the rocket into the sky.
Encourage the children to observe the rocket's trajectories and observe its flight characteristics, such as time, height, speed, and stability.
Have students launch rockets at various angles and observe differences in flight height and distance. This phase is exploratory, allowing students to see how angle affects trajectory.

5. Calculate height and speed of the vertical launch (optional)

Ask the teams to conduct only vertical (90°) launches, measuring the flight time and writing it in the table of the Student Worksheet.
Apply the formulas to calculate the maximum height that can be reached and the initial velocity of the rockets launched vertically.
After each launch, facilitate discussions and encourage the students to share their observations and insights: discuss factors that influence the rocket's flight, such as the design and importance of the fins, the amount of water, and the pressure applied.
Encourage critical thinking by asking questions about the forces at play, such as the role of air pressure and Newton's laws in rocket propulsion and flight (action-reaction).
Encourage the teams to modify their rocket designs, the amount of water and the pressure and conduct multiple launches, comparing the results and iterating on their designs to improve performance.

Image 4: getting ready for a vertical launch. Credits: UniversCiel

Reflection: (Discussion)

Encourage students to reflect on their experiences, asking questions. Ask what rocket is best to reach the stuck Astronauts.

Watch this video to see a rocket launch:

https://youtube.com/shorts/6Bq-uko5It8

Evaluation

Here are some evaluation approaches we can consider:

Observations: Observe the students' engagement, collaboration, and adherence to safety protocols during the activity.
Performance Assessment: Assess the performance of the rockets based on criteria such as stability, height achieved, flight duration, maximum pressure and accuracy of trajectory. (use the table in the Annex document below)
Data Analysis and Reflection: Have students analyse the data collected during the activity. Ask them to interpret their findings, identify patterns, and make connections to the scientific principles discussed.
Conceptual Understanding: Assess students' understanding of the scientific concepts related to the activity through quizzes, concept maps, or written explanations. Evaluate their ability to explain the principles of rocket motion, the forces involved, and the relationship between variables such as water volume, air pressure, and rocket performance.
Communication and Presentation: Have students present their rocket designs, launch results, and scientific findings to the class or in small groups. Evaluate their ability to effectively communicate their ideas, use appropriate scientific vocabulary, and convey their understanding of the concepts involved.
Integration with Curriculum: Assess the integration of the activity with the school curriculum by evaluating how well it aligns with learning objectives, content standards, and the development of specific skills within science, technology, engineering, and mathematics specially in projectile physics.

Curriculum

Science: The water rocket activity allows students to explore scientific concepts such as Newton's laws of motion, forces and motion, aerodynamics, pressure and Bernoulli’s equation. They can observe how these principles come into play during the rocket's launch and flight.
Physics: The activity provides a practical application of physics principles, including propulsion, thrust, trajectory (projectile physics), gravity, and energy transfer. Students can analyze the forces involved in rocket motion and understand how they affect the rocket's flight path.
Mathematics: Students can engage in mathematical calculations and data analysis by measuring launch distances, recording flight times, and graphing the relationship between variables such as water volume, air pressure, and rocket performance. They can also analyze data to identify patterns and make predictions.

Additional Information

This activity was proposed by NAEC Team Lebanon within the Sabir co-design project developed by the OAE Center Italy (Milan, 2-6 September 2024). For more information: link to OAE Center Italy webpage dedicated to the project.

This activity is available in other languages: French, Arabic, Turkish, Spanish, English, Italian, Slovenian (coming soon).