Designing an Experiment: Bottle Rocket Lab
DAY ONE
Introduction / Purpose
The purpose of this assignment is to practice designing a controlled experiment to test a hypothesis.
In this assignment, you will explore rocket flight and identify major factors that affect the altitude that a 2-liter bottle rocket can reach. Working in groups, you will design, build, and launch a 2-liter bottle rocket that is designed for maximum altitude. Each group will be responsible for testing one level of the Independent variable-amount of water in the rocket. You will also learn methods for measuring the altitude that the rocket reaches.
It is important know Newton’s Laws in order to better understand how a bottle rocket operates. Write Newton’s three laws in your own words:
1. ______
2. ______
3. ______
Main Idea
The altitude a 2-liter bottle rocket can reach is affected by four main factors:
1) the air pressure in the bottle
2) the amount of water in the bottle
3) the air resistance of the rocket
4) the stability of the rocket.
Ask a question and assign roles.
The question we will be addressing is
“What is the optimum amount of water to use in a water rocket?”
Assign Roles
Mission Control Specialist – Oversees project and rocket launching. Name: ______
Pressure Division Specialist – How much pressure is optimal? Name: ______
Liquid Fuel Specialist – How much fuel (water) is optimal? Name: ______
Aerodynamics Specialist – What is the most effective design? Name: ______
Do Background Research/Observations:
1. To the right, draw a visual
representation of what you
have observed of past rockets
2. To do background research. To do this, go to the following website http://www.ohio4h.org/sciencealive/rocketsaway.html Here you can see how the variables of amount of water, pressure, and weight affect the height/velocity/flight time. Answer the questions of the following page.
a. What did you discover about weight?
b. What did you discover about amount of water?
c. What did you discover about pressure?
Hypothesis:
Our group thinks that if we add ______mL of water to our rocket, then it will l aunch for ______seconds.
Note: For safety reasons, the air pressure inside the bottle cannot exceed 40psi so we will keep psi constant.
Remember, any good science experiment changes only one variable per experiment. This experiment is a test of varying water amounts.
On the following page, complete the following experimental guideline for our project. Each group will act as a different level of the independent variable (water amount) and we will use class data to see how much water will create the longest flight time. It is important when designing your experiment to only vary the amount of water.
You will complete through the third page before launching.
Design an Experiment
Title:
Hypothesis:
Independent Variable I.V:
Different amounts of water. We will add ______mL to compare to the rest of the class
Levels of I.V. / Control(no water) / Group 1’s
mL: / Group 2’s
mL: / Group 3’s
mL: / Group 4’s
mL: / Group 5’s
mL: / Group 6’s
mL: / Group 7’s
mL:
Number of trials you will conduct for each I.V. level (not to exceed 3) / 1
Dependent Variable:
Constants:
Now that you have designed your experiment, you can work together using the supplies provided to design the rocket you are going to launch with your level of I.V. and you are ready to build your rocket!
Below is the list of materials and equipment you can use to create your rocket. It is important to keep in mind, when designing, that the 2 liter bottle will be attached to the launch pad upside-down and needs to attach where you pour the soda from.
Additionally, keep in mind that in addition to water amount and pressure, there is weight to consider. Try to add just enough to your bottle to assist in creating good aeurodynamics without too much weight.
Brainstorm in the box (words and pictures) what you might add to your bottle.
Materials & Equipment
Empty 2-liter bottles
Rocket launch pad
Air pump with pressure gauge
Stopwatches
Cardboard, cardstock, paper
Duct tape or other waterproof tape
Scissors
Containers of water
DAY TWO
Test Experiment
Launching your rocket:
Safety Considerations:
· Anyone within 20 meters of the launch pad must wear safety goggles.
· Never put your head over a pressurized rocket.
· Stay low to the ground when launching rockets.
· Every launch must begin with a countdown: “5-4-3-2…1!”
· Pay attention when rockets are being launched. A “heads up” approach will help prevent you from being hit by a rocket. Use common sense.
Using the same assigned roles as before, the jobs during launch are:
a. Mission Control runs the stop watch and records the data
b. Pressure Specialist runs the air compressor
c. Fuel Specialist pours the fuel into the bottle
d. Aerodynamics Specialist sets the rocket on the launcher
Collecting Data:
Data Tables
Use the space below to construct data tables for your group’s trials. Refer to the Data Table Design Handout for guidelines and use a ruler.
Data Table 1(Quantitative): Independent Variable (I.V.) vs. Flight Time (don’t forget to include a column for the mean calculation of each level of the I.V.).
Data Table 2 (Qualitative): I.V. vs. Descriptive Flight Observations
Analyzing Data
Calculation Table 3: Independent Variable vs. Height of Rocket Flight
Note: The height that each rocket traveled can be calculated using a fairly simple formula:
Height = 1/2 (gravity) (t2)
gravity (g)= 9.8 m/sec2 / time(t) = 1/2 the total flight time in sec.Sample problem: Total flight time (T) for a rocket is 20 sec. T=20 sec
t=T/2 t=20/2 t=10 sec
Height = 1/2 (gravity) (time2)
Height (m)= 1/2 (9.8m/sec2) (10 sec2)
Height = 490 meters
Independent Variable(mL water) / Average Total Flight Time (T)
(sec) / t
t=T/2 / Height Calculations
Height = 1/2 (gravity) (t2)
(show work) / Height (m)
Graphs
Graph 1: I.V. vs. Average Rocket Total Flight Time (T)
Graph 2: I.V. vs. Average Height of Rocket Flight
Drawing Conclusions:
1. Was your hypothesis correct? Why or why not.
2. Was there anything in the experiment (including the whole class data) that could have caused an experimental error?
3. Explain how this lab applies to Newton’s laws