Physics: Ch. 1 – About Science

Physics: Ch. 1 – About Science

1. Briefly, what is science?
Science it the product of human curiosity about how the world works – an organized body of knowledge that describes order and causes within nature and an ongoing human activity dedicated to gathering and organizing knowledge about the world.
2. Throughout the ages, what has been the general reaction to new ideas about established “truths”?
The general reaction has been to forbid new ideas.
3. When the sun was directly overhead in Syene, why wasn’t it directly overhead in Alexandria?
Alexandria was farther north, at a higher latitude
4. Earth, like everything else illuminated by the sun, casts a shadow. Why does this shadow taper?
The shadow tapers because of the large size of the sun, certainly not a point source of light
5. How does the moon’s diameter compare with the distance between Earth and the moon?
Like the sun, the moon’s diameter is 1/110 the distance between earth and the moon.
6. How does the Sun’s diameter compare with the distance between the earth and sun?
The sun’s diameter is 1/110 the distance between earth and the sun.
7. Why did Aristarchus choose the time of a half moon to make his measurements for calculating the earth-sun distance?
At the time of a half moon he knew the angle between a line joining the moon and earth was at 90 degrees to the line joining the moon and the sun.
8. What are the circular spots of light seen on the ground beneath a tree on a sunny day?
The circular spots are pinhole images of the sun.
9. What is the role of equations in this book?
The equations are guides to thinking that show the connections between concepts in nature.
10. Outline some steps of the scientific method.
1. Observe
2. Question
3. Predict
4. Test Predictions
5. Draw Conclusion.
11. Distinguish among a scientific fact, a hypothesis, a law, and a theory.
The answer is as stated in the Summary of Terms
12. In daily life, people are often praised for maintaining some particular point of view, for the “courage of their convictions.” A change of mind is seen as a sign of weakness. How is this different in science?
Competent scientists must be experts at changing their minds.
13. What is the test for whether a hypothesis is scientific or not?
A scientific hypothesis must be testable.
14. In daily life, we see many cases of people who are caught misrepresenting things and who soon thereafter are excused and accepted by their contemporaries. How is this different in science?
Whereas mistakes or misrepresentations are given second chances in daily life, second chances are not given to scientists by the scientific community.
15. What test can you perform to increase the chance in your own mind that you are right about a particular idea?
See if you can state the position of an antagonist to the antagonist’s satisfaction, and compare it to how well the antagonist can state your position. If you can, and your antagonist can’t, the likelihood is that you are correct in your position.
16. Why are students of the arts encouraged to learn about science and science students encouraged to learn about the arts?
To know more than what’s in your bag of beliefs and attitudes is to expand your education.
17. Must people choose between science and religion?
No. Science and religion can work well together, and even complement each other. (Religious extremists, however, may assert that the two are incompatible.
18. Psychological comfort is a benefit of having solid answers to religious questions. What benefit accompanies a position of not knowing the answers?
One benefit is an open and exploring mind.
19. Clearly distinguish between science and technology.
Science is gathering knowledge and organizing it; technology puts scientific knowledge to practical use and provides the instruments scientists need to conduct their investigations.
20. Why is physics considered to be the basic science?
The other sciences build upon physics, and not the other way around.
23. What is the penalty of scientific fraud in the science community?
The penalty for fraud is professional excommunication.
24. Which of the following are scientific hypothesis?

a) chlorophyll makes grass green
b) earth rotates about its axis because living things need an alternation of light and darkness
c) tides are caused by the moon

a) Scientific Hypothesis
b) Speculation
c) Scientific Hypothesis
25. In answer to the question, “When a plant grows, where does the material come from? Aristotle hypothesized by logic that all material came from the soil. Do you consider his hypothesis to be correct, incorrect, or partially correct? What experiments do you propose to support your choice?
It is partially correct. Plant material comes partly from the soil, but mainly from the air and water. An experiment would be to weigh a pot of soil with a small seedling, then weigh the potted plant later after it has grown. The fact that the grown plant will weigh more is evidence that the plant is composed of more material than the soil offers.
26. When you step from the shade into the sunlight, the sun’s heat is as evident as the heat from hot coals in a fireplace in an otherwise cold room. You feel the sun’s heat not because of its high temperature (higher temperatures can be found in some welder’s torches) but because the sun is big. which do you estimate is larger; the suns radius or the distance between the moon and earth? Check your answer in the list of physical data on the inside back cover. Do you find your answer surprising?
The sun’s radius is approximately 7 x 10^8m. The distance between the earth and moon is about 4 x 10^8m. So the sun’s radius is much larger, nearly twice the distance between the earth and moon. The earth and moon at their present distance from each other would easily fit inside the sun. The sun is really big.
27. What is probably being misunderstood by a person who says, “But that’s only a scientific theory”?
It is the distinction between theory and hypothesis. In common usage, theory may mean a guess or hypothesis, something that is tentative or speculative. But in science a theory is a synthesis of a large body of validated information. The value of a theory is its usefulness.
28. The shadow cast by a vertical pillar in Alexandria at noon during the summer solstice is found to be 1/8 the height of the pillar. The distance between Alexandria and Syene is 1/8 earth’s radius. Is there a geometrical connection between these two 1 to 8 ratios?
Yes, there is geometric connection between the two ratios. As the sketch shows, they are approximately equal. From this pair of ratios, given the distance between Alexandria and Syene, the radius of the earth can be calculated.
29. If earth were smaller than it is, but Alexandria-to-Syene distance were the same, would the shadow of the vertical pillar in Alexandria be longer or shorter at noon during the summer solstice?
The shadow would be longer because on the smaller planet the angle of the pole would be greater relative to the sunlight. The ratio of the shadow to pole height would be greater than 1 to 8 as in the previous answer.
Go to book to study questions 21, 22, 30, 31, 32
30. To publicly change your mind about your ideas is a sign of strength rather than a sign of weakness. It takes more courage to change your ideas when confronted with counter evidence than to hold fast to your ideas.
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