Physics Chapter 1 Conceptual Questions
If two different theories describe experimental observations equally well, can one be said to be more valid than the other (assuming both use accepted rules of logic)?
No, neither of these two theories is more valid than the other. Experimentation is the ultimate decider. If experimental evidence does not suggest one theory over the other, then both are equally valid. A given physicist might prefer one theory over another on the grounds that one seems more simple, more natural, or more beautiful than the other, but that physicist would quickly acknowledge that he or she cannot say the other theory is invalid. Rather, he or she would be honest about the fact that more experimental evidence is needed to determine which theory is a better description of nature.
Certain criteria must be satisfied if a measurement or observation is to be believed. Will the criteria necessarily be as strict for an expected result as for an unexpected result?
Probably not. As the saying goes, "Extraordinary claims require extraordinary evidence."
What information do you need to choose which equation or equations to use to solve a problem?
A list of known and unknown variables can be helpful to choose an equation that can be used to solve a problem.
What determines the validity of a theory?
A theory must describe all aspects of any system that fall in the area where the theory is applicable. For a theory any experiment which is testable has to be performed to verify its validity. if a good quality experiment which is verifiable contradicts even the well established theory, then the theory must be modified or discarded entirely.
What should you do after obtaining a numerical answer when solving a problem?
Check to make sure it makes sense and assess its significance.
Identify some advantages of metric units.
Conversions between units require factors of 10 only, which simplifies calculations. Also, the same basic units can be scaled up or down using metric prefixes to sizes appropriate for the problem at hand.
Can the validity of a model be limited or must it be universally valid? How does this compare with the required validity of a theory or a law?
The validity of a model can be limited ex: Bohr Model. However, a theory or law must be universally valid.
What is the difference between a base unit and a derived unit? (b) What is the difference between a base quantity and a derived quantity? (c) What is the difference between a base quantity and a base unit?
a. Base units are defined by a particular process of measuring a base quantity whereas derived units are defined as algebraic combinations of base units. b. A base quantity is chosen by convention and practical considerations. Derived quantities are expressed as algebraic combinations of base quantities. c. A base unit is a standard for expressing the measurement of a base quantity within a particular system of units. So, a measurement of a base quantity could be expressed in terms of a base unit in any system of units using the same base quantities. For example, length is a base quantity in both SI and the English system, but the meter is a base unit in the SI system only.
. (a) What is the relationship between the precision and the uncertainty of a measurement? (b) What is the relationship between the accuracy and the discrepancy of a measurement?
a. Uncertainty is a quantitative measure of precision. b. Discrepancy is a quantitative measure of accuracy.
For each of the following scenarios, refer to Figure 1.4 and Table 1.2 to determine which metric prefix on the meter is most appropriate for each of the following scenarios. (a) You want to tabulate the mean distance from the Sun for each planet in the solar system. (b) You want to compare the sizes of some common viruses to design a mechanical filter capable of blocking the pathogenic ones. (c) You want to list the diameters of all the elements on the periodic table. (d) You want to list the distances to all the stars that have now received any radio broadcasts sent from Earth 10 years ago.
a.) The diameter of solar system is equal to 10^13m. So, the radius of solar system is equal to 5x10^12m. It is maximum distance of a planet from sun. The prefix used for a factor of 10^12 is tera-. Hence, the mean distance from sun to any planet is measured in tera-meter. b.) The diameter of typical virus is 10^-7m. So, it can be written as 100x10^-9m. The prefix used for a factor of 10^-9 is nano-. Hence the diameter of virus is 100nm. c.) The diameter of Hydrogen atom is 10^-10m and all other elements are bigger than hydrogen. So, it can be written as 100x10^-12m. The prefix used for a factor of 10^-12 is pico. d.) The distance travelled by signal sent from earth in 10 years is equal to multiplication of one light year into time. One light year is 10^16m so, distance travelled by signal is 10^16m x 10= 10^17m. It can be written as 100x10^15 m which is peta.
Some have described physics as a "search for simplicity." Explain why this might be an appropriate description.
because in physics the phenomenon happening around in the world is understood on the basic level. This study of world and phenomenon at most basic level is physics which make understanding of complex phenomenon also simple.
What are the SI base units of length, mass, and time?
meter, kilogram, second
What is physics?
the science concerned with describing the interactions of energy, matter, space, and time to uncover the fundamental mechanisms that underlie every phenomenon.
