The Solar Speedway!

Purpose of StudyI studied this because when I started my

experiment, gas was up to around 4 dollars a gallon. I wanted to learn about the different alternative energy resources that we have here on this earth. Getting energy from the sun is very clean, safe, and environmentally friendly. I have always loved meteorology-the study of the atmosphere and earth’s weather, and the sun affects our weather a lot. I also thought that it would be fun to have a miniature solar car, with a solar cell, and get to see right up close how a solar cell works. That is why I decided it would be a good, fun, and educational project to test how the angle of the sun affects solar intensity.

How do different angles of the sun affect the intensity of its

rays?

HypothesisI think that the higher up the sun is

in the sky, the more intense its rays will be- making my solar car move faster. I think this because it seems to get hotter as the sun moves higher in the sky.

VariablesIndependent- The different angles of the sun.Dependant- The intensity of its rays, (in this

experiment- how fast the car moves, and how many volts were collected from the sun by the solar cell.)

Controlled VariablesSome of my controlled variables are… 1- I will use the same car. 2- I will use the same solar cell. 3- I will test at the same location.

4- I will do the same amount of tests for each

time of the day.

Standard of ComparisonMy SOC, or my control group (which I have

had to pick) is how fast my car goes (or how many volts it gives off) at exactly 12:00. The reason I picked this one is because it is at the middle of the day, and will most likely have the least angle.

Materials“Klutz solar car book” kitPaperPencilYard stickString, at least 50 in. longProtractorStopwatchEither chalk or tape to mark starting line and finish lineTapeA pretty flat surface outside (at least 25 ft. long)

Procedure 11. Gather all the

needed supplies2. Assemble

your solar car.3. ON A SUNNY

DAY- Find a flat surface that is 25 ft. long, then mark off the starting line and finish line.

Procedure 24. Tape the string to the top of the yardstick.5. At 9:00 A.M.- Have someone hold the

yardstick straight up. 6. While they are holding the stick up, you

tape or hold the string on the ground, where the yardstick’s shadow is.

7. After you have taped (or are holding) the string to the ground, line the protractor up to the string.

8. Look at where the string is on the protractor, and this will determine the angle of the sun.

Procedure 3

9. Write down what the angle of the sun was for this time on your paper.

10. Get your stopwatch ready, and place your car on the starting line.

11. Once your car starts, start the stopwatch.12. Stop the stopwatch once the car has

crossed the finish line.13. Write down how fast your car went.

Procedure 4

14. Repeat your race 4 more times this hour, and record that data.

15. Each hour, get an average time of how fast your car went, and record it.

16. Do steps 5-15 for the following hours: 9:00, 10:00, 11:00, 12:00, 1:00, 2:00, 3:00

17. Clean all materials up, and head home.

18. Put data on computer, graphs, etc.

Procedure 519. Scan all of

results, look for flukes, and possible reasons why they happened.

20. Make a conclusion.

Qualitative Observations 1 At the beginning of my experiment, I noticed how it was probably hard for the small motor on my car to pull that big of a wheel on my car. I also noticed that the sun was not necessarily very high up in the sky, and the area I was in was not receiving much of the sun’s energy because it was not particularly hot. During my experiment, I definitely noticed that something was wrong. The angles of the sun that I measured were horribly low, not even half of a perfect 90 degree angle.

Qualitative Observations 2 Also, it seemed that my beginning

observation was correct- that the little motor was having a hard time pulling the big wheel of my car. I then decided it would probably be a good idea to test voltage given out by the solar cell, because my car was not moving very well. After the experiment, I noticed that the solar cell was only giving off about 1 volt of electricity, so that would explain why it was hard for the car to move off of only 1 volt of electricity.

Average time for the solar car to move 25 ft.

Seconds 22.346 32.464 48.72

Time 11:45 12:15 12:45

Angle of the sun

32 degree angle

34 degree angle

37 degree angle

Feet per second 1.12 0.77 0.51

Data Table 1

Data Table 2

How fast the car traveled at different times and angles

Feet per second 1.12 0.77 0.51

Time of the day 11:45 12:15 12:45

Angle of the sun

32 degree angle

34 degree angle

37 degree angle

Millivolts given off by Solar CarMilli-volts 1,045 1,058 1,076 1,070 1,051 1,050 1,054

Time of

Day 10:00 10:30 11:00 11:30 12:00 12:30 1:00

Angle of the Sun

23 degree angle

24 degree angle

24 degree angle

27 degree angle

31 degree angle

33 degree angle

32 degree angle

Data Tables 3

32 degree angle 34 degree angle 37 degree angle11:45 12:15 12:45

0

10

20

30

40

50

60

Average time for solar car to travel 25 feet (10-17-08)

Time of the Day and Angle of the Sun

Seconds

32 degree angle 34 degree angle 37 degree angle11:45 12:15 12:45

0

0.2

0.4

0.6

0.8

1

1.2

How fast the solar car moved (10-17-08)

Time of the Day and Angle of the Sun

Ft. Per S

econd

23 degree angle 24 degree angle 24 degree angle 27 degree angle 31 degree angle 33 degree angle 32 degree angle10:00 10:30 11:00 11:30 12:00 12:30 1:00

1,020

1,030

1,040

1,050

1,060

1,070

1,080

Millivolts given off by Solar Car (10-25-08)

Time of Day and Angle of the Sun

Millivo

lts

Analysis 1In my experiment, I

received more data than I thought I was going to get. When I tested how fast my solar car would move, I found that due to the season I was testing, the car did not move at my designated times which I set up in my procedure (9-3).

Analysis 2 However, I was able to find that at 11:45 the

car in average traveled 25 feet in approximately 22 seconds which is about 1.15 feet per second. I found that at 12:15 the car traveled 25 feet in approximately 32 seconds, which is about .71 feet per second. I found that at 12:45 the car traveled 25 feet in approximately 49 seconds, which is about .5 feet per second.

Analysis 3Due to only being able to receive that much

data, I decided to test also how many volts were given off by the solar cell on the car. I found that at 10:00 with the sun at a 23 degree angle the solar cell gave off 1,045 millivolts. I found that at 10:30 with the sun at a 24 degree angle the solar cell gave off 1,058 millivolts.

Analysis 4I found that at 11:00 with the sun at a 24

degree angle the solar cell gave off 1,076 millivolts. I found that at 11:30 with the sun at a 27 degree angle the solar cell gave off 1,070 millivolts. At 12:00 with the sun at a 31 degree angle the solar cell gave off 1,051 millivolts.

Analysis 5At 12:30 with the sun

at a 33 degree angle the solar cell gave off 1,050 millivolts. At 1:00 with the sun at a 32 degree angle the solar cell gave off 1,054 millivolts. It is also very worthy to note that this day that I measured the volts; I also tested my solar car each time.

Analysis 6The results were quite interesting- the

car never moved a full 25 feet, which means that somehow the sun’s intensity had changed in the past 8 days. Also, when I did the volts measurements, the highest reading was at 11:00, and then the rest went downward. Also, my first day when I tested, 11:45 had the fastest time, then all the times after that were slower.

Experimental Errors 1An obvious possible error in my experiment is

that I had to test my solar car and how fast it ran at 11:45, 12:15, and 12:45 because it would not run well at other times besides that.

Another possible error is that the wheels could have gotten scratched up, and didn’t work as well for later races.

It could be that in the fall/winter the sun’s rays could are more intense earlier in the morning, when in the summer its rays are more intense in the afternoon.

Another Possible Error is that in my first test with the time of how fast the solar car moved, on the last test (12:45) I had to use a mirror to restart the car a few times.

Experimental Errors 2Only Being able to

do my experiment at 11:45, 12:15, and 12:45 made it somewhat hard to compare it with my voltage experiment 8 days later at different (and more) times, and angles.

ConclusionIn my experiment, I wanted to know how the

angle of the sun affects the intensity of its rays. I hypothesized that the sun’s rays would be the most intense the closer they were to a 90 degree angle, because a 90 degree angle would mean the sun is straight up in the sky. After testing my hypothesis, I found that my solar car did not move its fastest (or did not receive the most volts) at 12:00.

Conclusion 2I found that 11:00 seemed to be the best time

for the solar car because when I tested, the car collected the most volts of electricity at 11:00 (which the sun was at a 24 degree angle, and other times of the day had angles in the 30’s) and during my 3 trials of 11:45, 12:15, and 12:45 the car moved fasted at 11:45 (with the sun at a 32 degree angle, while the others were 34 and 37.

Conclusion 3This means that

according to my data, my hypothesis is rejected, and that the angle of the sun can affect the sun’s rays, but the sun does not get more intense just because its angle is closer to 90 degrees.

Recommendations For Further Experimentation1

If I did my experiment again, one thing that I would definitely change is I would do my experiment in the summer. I would also (since it would be in the summer) be able to do more trials, and could get a better picture of the real answer to my question. The next step to my experiment would be to do mostly the same experiment here, except to do it for each season, like to see that say during the summer the sun is most intense at 2:00 (with the sun at a 78 degree angle), but in the winter the sun is most intense at 11:00 (with a 26 degree angle).

Recommendations for Further Experimentation2

I think that if I did that experiment, the sun would be more intense at different times and angles. The way that my experiment would help today’s society is that many people are choosing to convert to cleaner, safer, and cheaper energy- from the sun. My experiment helps to show how you could receive more energy from solar cells at different angles of the sun.

Bibliographywww.google.comwww.sciencebuddies.orgKlutz solar car book