Homework Assignment
Physics I Advanced Unit 1 HW 1
1. Explain the difference between a theory and a hypothesis and a theory and a law.
a) Explain the difference between a theory and a hypothesis

A scientific theory is an explanation of events and phenomena in the natural
world based on knowledge gained by many observations and experiments. A
theory is generally accepted as an accurate explanation, but it does not mean
that is correct. A theory can be disproved through testing, but a theory can
grow with new evidence. A theory is not a fact, but grows stronger and more
useful with more supporting evidence.

A hypothesis is an educated guess about a phenomenon or problem that can be
tested but has not been.
The main difference between a theory and a hypothesis is that a theory has been tested
and has not been disproved and a hypothesis is untested. A hypothesis that has been
tested and seems to be true can become the basis for a theory.
Examples in Physics
Theories:
Big Bang Theory, Kinetic (Molecular) Theory, General and Special
Theories of Relativity
Hypotheses:
lesser rate.
If more mass is added to the cart, then the cart will accelerate at a
b) Explain the difference between a theory and a law.

A theory is an explanation of events and phenomena in the natural world
based on knowledge gained by many observations and experiments. (see
original definition for more information)

A law is a statement about what happens in nature and seems to be true
all the time.
Theories and laws are closely related because they are based upon evidence and
testing. The difference between a theory and a law is in the purpose of each. A
theory is meant to explain why things happen, whereas a law is meant to
summarize. Laws are often summarized as equations.
A theory consists of all of the knowledge and understanding about events and
phenomena in the natural world. On the other hand, a law summarizes an observed
natural event or phenomenon, but does not explain why it happens. Also, as a theory
becomes more refined, it will change. A law generally describes one aspect of a theory,
so it does not change (even if the theory changes) unless specifically proved incorrect.
Examples:
Theory
Theory of Plate Tectonics (explains how the Earth's surface has developed and changed
over geologic time)
Law
Newton's Second Law of Motion (F = ma) This law is used to summarize the
relationship between mass and acceleration of moving objects as it relates to net force.
Notes
“A theory explains a phenomenon, accounts for all available data, is supported by a huge body of
evidence. Hypotheses are just guesses that need testing. Theories have heft, validity, gravity.”
--Ruth Levy Guyer
Science Vocabulary:



Phenomenon (singular)
Phenomena (plural)
Fact
o A close agreement by competent observers of a series of observations of
the same phenonmenon-Paul Hewitt
o The first edition of The American Heritage Dictionary defines a fact as "1.
Something known with certainty. 2. Something asserted as certain. 3.
Something that has been objectively verified. 4. Something having real,
demonstrable existence."
Here is a statement of fact, in the scientific sense:

Under normal circumstances, if a piano is dropped from a height, it will fall.
This is true no matter how many times the piano is dropped and no matter how many
different people drop it. They can all agree that the piano will fall. This is so even if they
don't personally drop it, or even see it drop. In other words, they have "objectively
verified" that the piano will drop. The piano itself is a tangible, measurable object, which
means it has "real, demonstrable existence."