PHYS 1040 (Anger)
Spring 2009
Homework 1 solutions
Chapter 1:
1. When discussing a controversial scientific idea with a friend you hear the
phrase “Well, it’s only a theory.” How would you explain the scientific
method to your friend? In particular, how would you differentiate between
a hypothesis and a theory?
A scientist trying to understand some observed phenomenon
proposes a hypothesis, which is a collection of ideas that seems to
explain what is observed. A body of related hypotheses can be
pieced together into a self-consistent description of nature called a
theory. In science, a good theory is one that explains reality very
well and that can be applied to explain new observations. A valid
theory also has failed no major tests of its validity.
2. How are scientific theories tested?
Theories are tested with experiments. The ability of a theory to
make predictions is another test.
3. Describe the role skepticism plays in science.
Without skepticism, any wild claim would be accepted as valid.
Skepticism is the demand for proof or evidence.
4. Speed can be defined as the ratio of distance traveled to the time required
for the trip:
!
speed = distance
time "v=d
t
How long does it take light to travel from the Sun to the Earth, a distance
of 1.496x1011m? Show your work and use powers-of-ten notation. The
speed of light is 3.00x108 m/s.
See attached.
5. (Problem 39) a) Use the information given in the caption to Figure 1-7 to
determine the angular size of the Orion Nebula. Give your answer in
degrees.
