Match Rocket Lab - Newton's 3rd Law

Match Rocket Lab
Physics Concepts:
Newton’s 1 st Law - Every object in a state of uniform
motion tends to remain in that state of motion unless an
external force is applied to it.
This we recognize as Galileo’s concept of inertia, and
this is often termed simply the "Law of Inertia."
Newton’s 2 nd Law – If an unbalanced (net) force acts on
an object, that object will accelerate (or decelerate) in
the direction of the force.
Newton’s 3rd Law – For every action force, there is an
equal and opposite reaction force.
A body at rest is considered to have zero speed (a constant speed).
So any force that causes a body to move is an unbalanced force.
Also, any force, such as friction, or gravity, that causes a body to
slow down or speed up, is an unbalanced force. This law can be
shown by the following formula.
F= ma
• F is the unbalanced force (vector)
• m is the object's mass (scalar)
• a is the acceleration that the force causes (vector)
Force and acceleration are both vector quantities. In this law
the direction of the force vector is the same as the direction of
the acceleration vector.
Vector and Scalar Quanities: An understanding of
vectors is essential for an understanding of physics and
Newton’s Second Law. A vector is a quantity that has two
aspects. It has a size, or magnitude, and a direction. In
contrast, there are quantities called scalars that have only
size.
If a quantity has only a size, it is called a scalar. Mass,
distance, speed, time and temperature are examples of
scalars.
If a quantity has a size and a direction, it is a vector
quantity. Force, acceleration, velocity, displacement,
gravitational field, torque, and electric and magnetic fields
are all vectors.

Materials:
• Kitchen matches
• Aluminum foil
• Large paperclips for the launcher
• Small paperclips to create the exhaust release space
Setup:
Cut small rectangular pieces of aluminum foil (about
2”x 3”). Fold the foil in half and wrap tightly around
the match holding a straightened small paperclip up
against the match. Fold the end of the foil down around
the match head to assure that no exhaust can escape out
the top. Make sure it is wrapped tightly. After
wrapping the foil, remove the paperclip and be sure not
to touch the foil and close the opening created by the
paperclip. Set the match on the larger launching
paperclip. Light a match and hold it under the head of
the wrapped match. When it ignites inside the foil, the
exhaust should escape out the opening and launch the
rocket (match).
• The small paperclip needs
to be straightened with all
bends removed so that it
can be used to create the
exhaust opening.
• The large paperclip is used
for the launcher as shown in
picture the left.

Questions to ask:
• What do you think will happen when you ignite the match?
Why?
• Which one of Newton’s laws applies to the launching of the
match rocket?
• What is the action that causes the reaction?
• What is the reaction?
• What factors can you change to make your match fly
further?
Explanation: Initially, everything in the setup is at rest because the net force is 0
(balanced) and the objects are in equilibrium. In order to cause
motion, a force has to act on some part of the setup. When you
ignite the foil covered match, the exhaust pushes out the opening
created in the foil. According to Newton’s Third Law of Motion,
for every action, there is an equal and opposite reaction. As the
exhaust pushes out (action), the rocket launches forward (reaction).
If students have trouble getting their rockets to launch, remind
them to wrap the foil tightly and be sure not to touch the foil after
they pull the straightened paperclip out to avoid closing the
exhaust escape route.
• Common misconception: Students often think that the action is
lighting the match and the reaction is the rocket launching. These are
not equal and opposite forces, so students need to be reminded to
consider that. Lighting the match does cause the exhaust to form, but
it is not one of the equal and opposite forces.
Student Lab Reports:
Students should create a lab report:
State Newton’s Third Law of Motion
Make a diagram of your lab setup and label each part
State the action
State the reaction
Measure the distance of each of your rockets and record
those distances
Record changes made to your rockets
Analyze your results and draw conclusions
National Standards:
• Content standard A – Science as Inquiry
• Content standard B – Physical Science
• Content standard E - Science and Technology