Soaring Straws
Goals:
 To collaboratively construct a straw rocket launcher.
 To determine the relationship between gravitational and elastic potential
energy.
Materials: scissors, rubber band, 3 plastic straws, meter stick, marker, metric ruler,
toilet paper tube, masking tape, balance.
Procedure: Part 1-Constructing the rocket and launcher
 Cut a rubber band and tape it across an open end of the toilet paper tube. The
rubber band should be taut but not over stretched. This will become your
launcher.
 Cut 3cm off of one of the straws.
 Lay the 2 other straws side by side, separated by the 3cm piece. Be sure to
line up all 3 ends of the straws evenly. Tape the straws together.
 Starting from the untapped end, mark off 1cm increments on one of the long
straws, using the marker and metric ruler. This will become your rocket.
Part 2: Launching practice
 Use a balance to find the mass of the rocket in grams. Record your
measurement.
 Place the two long ends of your rocket through the tube (they should hang out
of the bottom of the tube) so that the short end rests on the rubber band.
 Practice launching your rocket by grasping the bottom straw lengths and
gently pulling downward and releasing. Caution: Be sure to aim your rocket
upwards and NOT toward a classmate! Repeat several trials until you are
comfortable with the procedure.
Part 3: Calculations:
 You will be recording two different measurements with your rocket launcher
onto your data table:
1. The amount of the stretch of your rubber band. This can be observed
by recording the centimeter marks on the rocket base from the bottom
of the launch tube.
2. The height that your rocket travels. This can be observed by having a
group member hold the meter stick at the zero mark directly above the
top of your launcher.
 Your group should launch your rocket using three (3) different amounts of
stretch. Record the average height for each stretch trial. Each stretch level
should include three (3) trials from which to obtain an average height.
 Using the formula for Gravitational Potential Energy:
GPE=mgh
(where m=Mass of the rocket; g = 10m/s2; h=Height the rocket soared)
Calculate the GPE for each stretch amount.
Soaring Straws Data Table
Mass of the straw rocket:
Amount of
stretch (cm)
Heighttrial 1 (m)
Heighttrial 2 (m)
Heighttrial 3 (m)
Average
height (m)
GPE
Reflection Questions
1)
2)
Which variable in your data table is the manipulated variable? Which was the
responding variable? How do you know? (what variable did you change for each set
of trials and which variable responded to those changes?)
In this lab, what measurement is related to the elastic potential energy?
3)
Using a sheet of graph paper, make a graph of your results. Show GPE on the
vertical axis and the amount of stretch on the horizontal axis. What conclusions can
you make by interpreting the graph? (What is the relationship between GPE and
EPE?)
4)
When you release the rocket, what kind of energy does the rocket have just after
takeoff? What are the GPE and EPE at this same point?
5)
You measured the GPE of your rocket at its maximum height in each trial. What
can you predict the kinetic energy of your rocket will be at takeoff?
Reflection Questions
6)
Which variable in your data table is the manipulated variable? Which was
the responding variable? How do you know? (what variable did you change for each
set of trials and which variable responded to those changes?)
The amount of stretch of the rubber band was the manipulated variable. The height of the flight was the
responding variable.
7)
In this lab, what measurement is related to the elastic potential energy?
The change in the amount of the stretch is the elastic potential energy.
8)
Using a sheet of graph paper, make a graph of your results. Show GPE on
the vertical axis and the amount of stretch on the horizontal axis. What conclusions
can you make by interpreting the graph? (What is the relationship between GPE
and EPE?)
The longer the stretch of the rubber band (EPE) the higher the flight of the rocket (GPE). This is a direct
relationship
9)
When you release the rocket, what kind of energy does the rocket have just
after takeoff? What are the GPE and EPE at this same point?
Kinetic energy. EPE is at max just before take off and GPE is zero. As the rocket flies, EPE is decreasing
and GPE is increasing until the rocket reaches max height. Then GPE is max and EPE is zero.
10)
You measured the GPE of your rocket at its maximum height in each trial.
What can you predict the kinetic energy of your rocket will be at takeoff?
Kinetic energy would be max and then gravity takes over an slows the rocket down until it actually stops at
the height of its flight.