Week 1 - Chapter 1 - Introduction of Science and Realm of Physics Flashcards
1What are the general truths of nature that science consists of?
Theories and Laws
We can only discover and understand them.
What is concerned with describing the interactions of energy (electricity), matter (mass), space (distance), and time, and it is especially interested in what
fundamental mechanisms underlie every phenomenon?
Physics
Physics is the foundation of many important disciplines and contributes directly to others.
What is a representation of something that is often too difficult (or impossible) to display directly?
A model
Newton’s theory of gravity does not require a model since we can observe it with our eyes.
However, the kinetic theory of gases, on the other hand, is a model in which a gas is viewed as being composed of atoms and molecules.
Atoms and molecules are too small to be observed directly with our senses—thus, we picture them mentally to understand what
our instruments tell us about the behavior of gases.
What is an explanation for patterns in nature that is supported by scientific evidence and verified multiple times by various groups of
researchers?
A theory
Some theories include models to help visualize phenomena, whereas others do not. For example, Newton’s theory of Gravity does not require a model or mental image because we can observe the objects with our own senses.
What uses concise language to describe a generalized pattern in nature and described the phenomena in nature and is supported by scientific evidence and repeated experiments?
Often, this can be expressed in the form of a single mathematical equation.
A law
Newton’s second law of motion
F=ma
How are theories and laws similar?
Laws and theories are similar in that they are both scientific statements that result from a tested hypothesis and are supported by scientific evidence.
How are theories and laws dissimilar?
The biggest difference between a law and a theory is that a theory is much more complex and dynamic.
A law describes a single action, whereas a theory explains an entire group of related phenomena. And, whereas a law is a postulate (a thing suggested or assumed as true as the basis for reasoning, discussion, or belief.) that forms the foundation of the scientific method, a theory is the end result of that process.
What does the models, theories, and laws we devise sometimes imply?
The existence of objects and phenomena as yet unobserved
This is relevant to the discovery of black holes
How do scientists inquire and gather information about the world?
Using a process called the scientific method
What does the word physics mean and what did it encompass in ancient times?
Physics comes from Greek, meaning nature.
The study of nature came to be called “natural philosophy” and encompassed many fields, including astronomy, biology, chemistry, physics, mathematics, and medicine.
Over the last few centuries, the growth of knowledge has resulted in ever-increasing specialization and branching of natural philosophy into separate fields, with physics retaining the most basic facets.
What did physics develop into from the Renaissance to the end of the 19th century? Why was it transformed?
Classical physics
It was transformed into modern physics by revolutionary discoveries made starting at the beginning of the 20th century.
What are the Limits on the Laws of Classical Physics? (3)
For the laws of classical physics to apply, the following criteria must be met:
- Matter must be moving at speeds less than about 1% of the speed of light.
- The objects dealt with must be large enough to be seen with a microscope.
- Only weak gravitational fields (such as the field generated by the Earth) can be involved.
What two revolutionary theories does Modern Physics consist of that is not a part of classical physics after the beginning of the 19th Century?
Relativity - must be used whenever an object is traveling at greater than about 1% of the speed of light or experiences a strong gravitational field such as that near the Sun.
Quantum mechanics - must be used for objects smaller than can be seen with a microscope.
From what you are learned, what describes the behavior of small objects traveling at high speeds or experiencing a strong gravitational field?
Relativistic quantum mechanics
What can all physical quantities can be expressed as combinations of? (4)
The four fundamental physical quantities:
- Length
- Mass
- Time
- Electric current
How do we define a physical quantity? (2)
Either by:
- Specifying how it is measured or:
- Stating how it is calculated
For example, we define distance and time by specifying methods for measuring them (meters and seconds), whereas we define average speed by stating that it is calculated as distance traveled divided by time of travel (example km/h)
What are the standardized values we use as measurements of physical quantities?
Units
For example, the length of a race, which is a physical quantity, can be expressed in units of meters (for sprinters) or kilometers (for distance runners).
What are the two major systems of units used in the world called?
How were these two systems derived?
SI units and English units
English units were historically used in nations once ruled by the British Empire and still widely used in the US.
SI units are derived from the French Système International.
Name the four fundamental physical quantities and their fundamental SI units.
Length = meters (m)
Mass = kilograms (kg)
Time = seconds (s)
Electric Current = amperes (A)
What do you call physical quantities, such as force and electric charge, that are expressed as algebraic combinations of the four fundamental units (example, speed is length divided by time)?
Derived units
Why is the metric system convenient? (2)
The metric system is convenient for scientific and engineering calculations because the units are categorized by factors of 10.
Units can be used over extremely large range of values by using the appropriate suffix.
Metric System Practice (9)
Name the metric prefix
- 10^15
- 10^12
- 10^9
- 10^6
- 10^3
6 10^0 - 10^ -2
- 10^ -3
- 10^ -6
- 10^ -9
- 10^ -12
They are indicative of how many zeroes the number has.
- Peta
- Tera
- Giga
- Mega
- Kilo
- No prefix; single unit!
- Centi
- Milli
- Micro
- Nano
- Pico
What is the order of magnitude?
This refers to the scale of a value expressed in the metric system. Each power of 10 represents a different order of magnitude.
For example, 800 = 8 x 10^2 and 450 = 4.5 x 10^2 which means both of these numbers belong to the same order of magnitude: 10^2
Order of magnitude can be thought of as a ballpark estimate for the scale of a value like the diameter of an atom and the diameter of the sun: 10^-9 vs. 10^9
Unit Conversion and Dimensional Analysis (Review)
Let us say that we want to convert 80 meters (m) to kilometers (km).
- List the units you have and the units you want to convert them to.
- Determine a conversion factor relating meters to kilometers. conversion factor is a ratio expressing how many of one unit are equal to another unit.
For example, there are 12 inches in 1 foot, 100 centimeters in 1 meter, 60 seconds in 1 minute, and so on. In this case, we know that there are 1,000 meters in 1 kilometer.
- Now we can set up our unit conversion. We will write the units that we have and then multiply them by the conversion factor so
that the units cancel out
Note that the unwanted m unit cancels, leaving only the desired km unit. You can use this method to convert between any types
of unit.
See Flipside.
