Clay Heebner and Matt Spearly Linear Motion Device Experiments Our first experiment was a test to find which direction the propeller should spin in order to provide forward propulsion. After researching we found that an angled blade should catch the air and push it back. From here we designed an experiment to test the direction a propeller should spin. Hypothesis: A propeller must cut first with the upper part of the blade into the; this throws air behind the propeller. Materials: Light propeller from kite, stopwatch, and tape Independent Variable: Direction the propeller is spinning Dependent Variable: Time it takes for propeller to hit ground Procedure: 1. Mark one side of the propeller with a piece of tape 2. Hold propeller at a height of six feet with tape facing up and take notice of which way the blades are angled 3. Spin propeller clockwise as another student starts stopwatch 4. Stop the time when propeller hits ground 5. Record time 6. Repeat for another time 7. Hold propeller at the same height with the tape facing up 8. Repeat steps 3-6 but spin propeller counterclockwise Direction of Spin Clockwise 1 Clockwise 2 Counter Clockwise 1 Counter Clockwise 2 Time (s) 1.31 1.32 .77 .84 Part that Cut Air First Upper Upper Lower Lower The results of the test above show that when the propeller was spun clockwise, it stayed in the air longer. This because it was taking air from above it and throwing it behind, which provided lift. The Counter clockwise spin took air from under it and threw it up; this brought it to the ground faster than the clockwise spin. The results proved the research we had done was correct and our hypothesis was correct. Our second experiment went along with both air resistance and the corkscrew effect. The corkscrew effect is the spiraling air flow that is made when air has passed through the spinning propellers. Hypothesis: With more holes in the paper, air resistance will decrease and paper will fall at a faster rate. Materials: Piece of paper, scissors, and stopwatch Independent Variable: Amount of holes in paper Dependent Variable: Time it takes paper to hit ground Procedure: 1. Take whole sheet of paper and hold at a height of six feet 2. Drop the sheet and someone else starts the stopwatch 3. Stop the stopwatch when the paper hits the ground 4. Record time 5. Cut one hole 1” by 1” in the center of the paper 6. Repeat steps 2-4 7. Cut another whole in the paper 8. Repeat steps 2-4 9. Repeat steps 2-7 up to eight holes Number of Holes in Paper 0 1 2 4 5 3 6 7 8 Time to Hit Ground (s) 2.56 2.36 2.27 2.43 2.06 2.17 2.06 2.13 2.25 Time to Fall vs Holes in Paper 3 2.5 2 1.5 Time (s) 1 0.5 0 0 1 2 3 4 5 6 7 8 The results of this test are hard to interpret; the time has an overall drop but it fluctuates. One observation we made was that the pattern of the holes had an effect on the way the paper fell. Sometime the pattern would let it fall on a straight downward path, while others would make it swing back and forth on its decent. This then had an effect on the time. However, it did demonstrate that an objects movement can be effected by the pattern of holes through it. This will be helpful in creating our linear motion device. We decided to change the experiment to combat the flaws with the last experiment. We had to try to make the paper fall in a more stable manner and get rid of the variable of the pattern of holes in the paper. Hypothesis: With more holes in the paper, air resistance will decrease and paper will fall at a faster rate. Materials: Piece of paper, scissors, ruler, and a stopwatch Independent Variable: Size of hole in middle of paper Dependent Variable: Time it takes paper to hit ground Procedure: 1. Take a whole sheet of paper and hold at a height of six feet 2. Drop sheet as another person starts the stopwatch 3. Stop stopwatch when paper hits the ground 4. Record time 5. Cut a hole 1” by 1” in the center of the paper 6. Repeat steps 2-4 7. Increase the dimensions of the whole by 1” both ways 8. Repeat steps 2-7 till Size of Whole 0 1” by 1” 2” by 2” 3” by 3” 4” by 4” 5” by 5” Time to Hit Ground 2.12 2.08 2.08 1.96 1.75 1.78 Time to Fall vs Hole Size 2.5 2 1.5 Time (s) 1 0.5 0 0 1" 2" 3" 4" 5" The data of this test was far more stable than it was in the last test. There is a downward movement in time as the size of the whole in the paper becomes larger. At first there is little change and this was partially due to the papers instability which causes some variation; still, at sizes 3” by 3” and 4” by 4” there were significant drops. Also as the hole size became larger, the stability did increase.