Bay Area Scientists in Schools Presentation Plan
Balloon Rocket Cars: Newton’s 3rd Law of Motion
Lesson Name
Presenter(s)
Grade Level
2nd
Standards Connection(s) Physical science, mechanics, modeling
Basic lesson plan
Abstract and Background:
rd
Newton’s 3 law of motion states: for every action, there is an equal and
opposite reaction. Whenever a body exerts a force on a second body, the
second body exerts a force—of equal magnitude and opposite direction—
on the first. In other words, there is no such thing as a unidirectional
rd
force. In this lesson, we will demonstrate Newton’s 3 law with multiple
real-world, relatable examples. Finally, the students will build balloonpropelled rocket cars to illustrate the principles of this law.
Notes & questions
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Throughout the lesson, students will have a chance to make predictions
and hypotheses about action and reaction. They will also learn about how
models are used to understand scientific phenomenon.
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Vocabulary/Definitions:
3 – 6 important (new) words (On board front center, pre-written on printer paper & posted):
• force: a push or a pull
• model: a simpler version of something, which we can
easily study
• hypothesis: a testable prediction of what will
• action/reaction: the application of force and the
happen
response to that force
• motion: movement of a body
• Newton’s Third Law of Motion- for every action, there is an equal and opposite reaction.
Materials:
Brought to class: Material kits for demos and rocket car construction.
Classroom Set-up:
An open space of ideally 4ft x 12ft. Students arranged in three groups.
Surfaces or desk to build the balloon rocket cars on.
Classroom Presentation
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1. Personal Introduction & Topic Introduction: 10 Minutes
(Varies by presenter) Introduce yourselves, your interest and role in science.
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(Drop item on the ground) Do any of you know what caused the object to fall
on the ground? (Get ideas, coaxing the answer: gravity.) Gravity is one type
of force. A force is a push or a pull. (Write the keywords and definitions on
the board. Demonstrate a force by pushing or pulling on an object or on each
other.) A long time ago, in the 1600s, a scientist named Isaac Newton saw an
apple fall to the ground. This inspired him to think about all the kinds of
forces that push and pull around us. He made several rules to explain this.
Today, we will talk about one of these forces, which explain what happens
when a force is applied to an object.
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2. Learning Experience(s): 45 minutes
Front of class demonstration
Ask for a volunteer to sit on the skateboard next to a wall. Ask the class what
will happen if the student pushes off the wall with his feet. Explain that by
making a prediction, they are formulating their own hypotheses. Encourage
the students to use the words “force” in their hypothesis.
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Ask the child on the skateboard to push off the wall. Was their hypothesis
correct? What was the force applied? Was there motion? What was the
action? What was the reaction? Draw a simple diagram of what happened
on the board. Use arrows to show the directions of the force and the
opposite force.
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1st law: object in motion stays
in motion unless acted upon
by a force.___________________
2nd law: Body of mass m
subjected to force F undergoes
an acceleration a. (F=ma).____
Push
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Lead a discussion to explain Newton’s Third Law such that the class
understands action and reaction. Explain with real-world examples, like
swimming, paddling, being thrown back on a rollercoaster, rockets. Ask the
students for their own examples, and ask them to identify the action and
reaction in every example.
You can use a table like this on the board for this brainstorming session:
Example
Action
Reaction
Swimming
Stroke of arm forward
Resistance of water
backwards
Rocket
Engine propelling
Rocket goes upward
downward
Child and skateboard
Pushing feet off wall
Skateboard goes
forward
backward
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Compare a rocket to a balloon with the air escaping. In a rocket, the burning
fuel and expanding gas shoots downwards (action) and propels the rocket up
(reaction). Likewise, in a balloon, the released air shoots in one direction
(action), and the balloon flies in the opposite direction (reaction). Draw
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other force diagrams on the board to illustrate some of the other examples.
Second demonstration
1) Blow up a balloon
2) Hold the end closed and tape a piece of straw to it, perpendicular to
the opening of the balloon.
3) Thread a string through the straw and tape the ends of the string so
that the string is taut on both sides.
4) Before releasing the balloon, ask the students for their hypotheses on
what the balloon will do once you release it.
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balloon
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straw
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string
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Let go of the balloon. Were their hypotheses correct? What was the action?
What was the reaction? Draw a force diagram on the board of the action and
reaction of the balloon.
Making Balloon Rocket Cars
Divide the class into three groups. One volunteer will supervise each of the
groups. Distribute the materials to each student:
1) 4 marshmallow wheels
2) 2 wooden skewers
3) 2 straight straws
4) 1 bendy straw pre-taped to a balloon
5) 1 piece of cardboard
Directions:
1) Thread the skewers through the straight straws.
2) Push the marshmallow wheels onto all four ends of the skewers
3) Tape the cardboard such that it connects the two sets of straws, as
the body of the car.
4) Tape the straw with the balloon on top of the piece of cardboard. This
will be the “rocket.”
5) Have the student write their name on the cardboard paper.
6) Blow up the balloon through the straw. And plug the hole of the straw
with a finger. When you left the balloon deflate, the car will be
propelled forward
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Representation of completed car:
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After the students are finished building their cars, they can race their cars in
the empty area of the room. Lay the measuring rope down along the “race
track.” As the students propel their cars, this can be used to measure how
far the cars will go. These results can be charted or graphed with time
permitting. If there is time, ask the students to design other experiments and
hypotheses with their cars: Does the degree of inflation on the balloon
matter in how far the car will go? Why? Emphasize that if you change the
degree of action, the reaction will also change.
3. Wrap-up: Sharing Experiences and Building Connections: 5
minutes
What was the action in our rocket cars? The reaction? Draw a force diagram
with arrows to illustrate this. Reinforce Newton’s Third Law once again. How
is our rocket car like rockets in real life? You can watch recorded shuttle
launches by NASA online.
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4. Close: 5 Minutes
Clean-up. All rocket car materials back in plastic bags. Thanks and good-bye!
TOTAL 65
Minutes
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Follow-up Possibilities
- NASA Rocket Activities (Including Balloon Rocket Cars)
http://exploration.grc.nasa.gov/education/rocket/TRCRocket/RocketActivitiesHome2.html
Reading Connections:
- Give It a Push! Give It a Pull!: A Look at Forces by Jennifer Boothroyd http://www.amazon.com/GivePush-Pull-Lightning-Exploring/dp/0761360565
- Isaac Newton and Physics for Kids: His Life and Ideas with 21 Activities by Kerrie Logan Hollihan
http://www.amazon.com/Isaac-Newton-Physics-Kids-Activities/dp/1556527780/ref=pd_sim_b_1