Clearspring Elementary School Stem Fair April 4, 2013 Well Designed investigation (An Experimental Research)

Grade 4 and 5 Planning packet

Guidelines: An entry must be an experiment to prove that a hypothesis was correct or incorrect. The components should include: * Testable Question: A question that can be answered through an investigation. *Hypothesis: A testable explanation (if – then statement) based on an observation, experience or scientific reason. It includes the expected cause and effect in a given circumstance or situation. *Variables(s): The factors in an investigation that could affect the results. The independent variable is the one variable the investigator chooses to change. The dependent variable changes as a result of, or in response to, the change in the independent variable. Controls and control groups are used for comparisons. *Materials: All materials needed for completing the investigation are listed. *Directions: A logical set of steps to complete the procedure are listed. *Repeated or multiple trials: Repeating the procedure several times for validity and reliability. *Data collection: The results of the investigation, usually recorded as observations, table, graph, chart diagram, etc. *Conclusion (or summary): Form a conclusion – A Statement, supported by evidence, identifying the pattern (repeating cycle) or trends (general drift, tendency, or direction of a set of data) based on an analysis of the data collected during the investigation. Write a conclusion – the closing paragraph of a report which addressed the investigation question, critiques the hypothesis, and explains the results. It demonstrates a full and complete understanding and includes the synthesis of information, supporting details, accurate use of terminology, and application of information. *communication: present your findings on a project board set up. Results can be displayed by using drawings, photographs, graphs, tables, text or another visual aid.

Example provided by Rithvik Bhogavalli

Question If I increase the size of the balloon, will the hover craft go farther? Hypothesis My hypothesis is that I can simulate the motion of a hovercraft using air escaping from

balloons. If I increase the size of the balloon then the hovercraft will go farther because bigger balloons carry more air and can keep the craft in the air longer.

Materials

The materials that I used in this project are: 1 small balloon 1 medium balloon 1 large balloon 1 CD A roll of Tape 2 fans 1 balloon pump 1 pop- top Tape measure Flat surface

Variables

1. Independent Variable: The independent variable is the amount of air you put in the

balloon. This is the independent variable because in my experiment, I change the amount of air that I put in each balloon. 2. Dependent Variable: The dependent variable is the distance traveled by the

hovercraft. This is the dependent variable because the distance traveled is affected by the air in the hovercraft’s balloon. 3. Control Variables: The control variables in this experiment are the travel surface,

hovercraft, and the fans providing thrust. These need to be controlled, or the experiment will not be even.

Procedure

1. Take a pop-top lid of a plastic water bottle. 2. Get an old CD. 3. Tape the pop-top to the top and center of the CD. 4. Blow a balloon and pinch the neck.

5. Put the base on the ground.

6. Plug in one or two fans that provide thrust. 7. Put the base in front of the fans. 8. Put the blown balloon on the base.

9. Leave open the balloon’s neck and let the air flow out. That air flowing out under the CD provides lift and the hovercraft hovers. 10. Observe the base levitate and pushed forward by air provided by the fans.

11. See how far the balloon goes and measure.

12. Try with a bigger balloon each time. 13. Record the distance travelled by the hovercraft during each trial.

Data & Graphs

I repeated the experiment three times with three different sizes of balloons and

recorded the distance traveled by the hovercraft. The data is shown in the table below: Distance Hovered (in)

Error

Balloon Size

Low

Medium

High

Average Lower

Upper

6”

4

6.5

11

7.167

3.167

3.83

12”

86

99

103

96

10

7

16”

193

198

206

199

6

7

Table 1: Data from the experiment The average distance travelled by each size of the balloons is calculated and plotted in the line graph below:

Effect of Balloon Size on Hovering Distance Distance Travelled (inches)

250 200 150 100 50 0 6

12

16

Balloon Size (inches)

Figure 1: Graph showing the effect of balloon size over distance travelled

The error bars for each size of the balloons in the graph show the range of distances travelled by that balloon. The data and graph show that the 6” balloon can barely help the hovercraft move, likely because the lift provided by this balloon is not much more than the gravity’s effect on the hovercraft (i.e. weight of the hovercraft). With bigger balloons, the distance travelled by the hovercraft increases as expected.

Conclusion In the experiment, my hypothesis was mostly correct. In the beginning of the experiment, when I did not use the fans to cause thrust, the hovercraft went around in circle not going anywhere. Then I had to change that by adding thrust using two fans. The graph shows that as the balloon size increased, the distance traveled by the hovercraft increased almost linearly. With the 6” balloon, the hovercraft barely moved at all. This indicates that even smaller balloons are not helpful because they cannot overcome

the force of weight and inertia of the hovercraft. I also note that for the balloon hovercraft to hover, the balloon nozzle should fit the cap tightly. With the medium balloon the craft did travel farther but the nozzle did not fit the cap properly and some of the air leaked through the fit. When I tried the smaller and bigger balloon, the nozzle fit well so the craft did move better. My conclusion is that the more air you put in the balloon on the balloon hovercraft, the

farther it will go. Also the nozzle should fit the pop- top and the craft needs a source of thrust.

Future Work In my experiment, I never thought about putting weight on the hovercraft. Hovercrafts are supposed to be used for transportation. I think that next time I could try to put weight on the hovercraft. Also, instead of plugging fans in and putting them behind the craft, I might be able to find a fan small and light enough and put on the craft itself so it might go farther. That is because when you plug in the fans, after the hovercraft goes a certain distance, the air from the fans can’t reach it and it stops. If the fans are on the hovercraft, then it will never lose thrust unless the fans stop working.

Additional resources: http://www.sciencebuddies.org/science-fairprojects/project_display_board.shtml#sampless to view.