Physics Ch. 1

What is the order of magnitude of 297,395?

Log10(297,395) = 5.47. So the order of magnitude is 10^6.

meter

SI unit for length, abbreviated m

kilogram

SI unit for mass, abbreviated kg

What is the difference between SI and English units?

Si units - international system of units that scientists in most countries have agreed to use (i.e. m, L, kg). English units - system of units that is used widely only in the US (i.e. ft, gal, lbs)

What determines the validity of a theory?

Experimental tests produce results that confirm the theory.

If a quantity is dimensionless, what are its units?

The quantity has no units.

What is an order of magnitude?

The size of a quantity as it related to a power of 10.

Why are significant figures useful?

They are used to express the precision of a measuring tool used to measure a value

method of adding percents

the percent uncertainty in a quantity calculated by multiplication or division is the sum of the percent uncertainties in the items used to make the calculation

percent uncertainty

the ratio of the uncertainty of a measurement to the measured value, expressed as a percentage

order of magnitude

the size of a quantity as it relates to a power of 10

standard deviation of mean

the standard deviation of a set of measurements divided by the square root of the number of measurements in the set

How is the second defined in the metric system now?

time it takes for certain number (~9 Billion) vibrations of a Cesium atom

What are some examples of dimensions?

time, mass, mass squared (M^2), 1/length (1/L) ...

derived units

units that can be calculated using algebraic combinations of the fundamental units

significant figures

used to express the precision of a measuring tool used to measure a value

estimation

using prior experience and sound physical reasoning to arrive at a rough idea of a quantity's value; sometimes called an "order-of-magnitude approximation," a "guesstimate," a "back-of-the-envelope calculation", or a "Fermi calculation"

standard deviation

a computed measure of how much scores vary around the mean score

uncertainty

a quantitative measure of how much measured values deviate from one another

What ratio (what divided by what?) is a conversion factor?

a ratio how many of one unit are equal to another unit: for example the first unit divided by the equal number of the other

conversion factor

a ratio that expresses how many of one unit are equal to another unit

dimensionless

quantity of dimension 1 or a pure number

model

representation of something often too difficult (or impossible) to display directly

physics

science concerned with describing the interactions of energy, matter, space, and time; especially interested in what fundamental mechanisms underlie every phenomenon

How should the conversion factor be chosen/mathematically arranged?

so the old unit cancels out

What are base units?

standard for expressing the measurement of a base quantity within a particular system of units; defined by a particular procedure used to measure the corresponding base quantity

base unit

standard for expressing the measurement of a base quantity within a particular system of units; defined by a particular procedure used to measure the corresponding base quantity

units

standards used for expressing and comparing measurements

metric system

system in which values can be calculated in factors of 10

English units

system of measurement used in the United States; includes units of measure such as feet, gallons, and pounds

theory

testable explanation for patterns in nature supported by scientific evidence and verified multiple times by various groups of researchers

second

the SI unit for time, abbreviated s

accuracy

the degree to which a measured value agrees with an accepted reference value for that measurement

precision

the degree to which repeated measurements agree with each other

discrepancy

the difference between the measured value and a given standard or expected value

experimental difference

the difference between two values being compared

SI units

the international system of units that scientists in most countries have agreed to use; includes units such as meters, liters, and grams

reliable standard unit must be...

-repeatable -accurate -transportable -long lasting

pico (p)

10^-12

femto (f)

10^-15

milli (m)

10^-3

micro (μ)

10^-6

nano (n)

10^-9

Tera (T)

10^12

kilo (k)

10^3

Mega (M)

10^6

Giga (G)

10^9

speed of light

3.00 x 10^8 m/s

What is the difference between accuracy and precision?

Accuracy - how close a measurement is to the accepted reference value for that measurement. Precision - how close the agreement is between repeated independent measurements

Physics is devoted to the understanding of what?

All natural phenomena which means all natural things that occur

How is a physical quantity defined?

Characteristic or property of an object that can be measured or calculated from other measurements.

What law ties together food calories, batteries, heat, light, and watch springs? What does it state?

Conservation of energy. Energy can change form but is never lost.

Describe the scope of physics. Describes the most basic understanding of phenomena.

Describes the interactions of matter, space, and time.

What is discrepancy or measurement error?

Difference between the measured value and an expected value.

Physics can be used to describe what aspects of smartphones?

Electricity flow through circuits and GPS.

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?

Models only need be accurate in describing certain aspects of a physical system. A theory or law must be valid in all situations.

steradian

Solid Angle of cone; ϴ= 1 steradian; 4pi steradians in a sphere

What is a unit?

Standards used for expressing and comparing measurements.

experimental error

The difference between the true value of a measurement and the measured value

Is the equation v=a*t dimensionally consistent?

Yes. [v] = [L]/[T] = [L]/[T^2] * [T] = [L]/[T].

What is a Fermi calculation?

an estimation

Is an order of magnitude designed to act more like an exact quantity or as a ballpark estimate?

ballpark estimate

How is the kg defined in the metric system now?

based on mass of a standard object at NIST

physical quantity

characteristic or property of an object that can be measured or calculated from other measurements

Is area a base or derived quantity?

derived

How do base units and quantities differ from derived quantities and units?

derived quantity- physical quantity defined using algebraic combinations of base quantities derived units- units that can be calculated using algebraic combinations of the fundamental units.

law

description, using concise language or a mathematical formula, of a generalized pattern in nature supported by scientific evidence and repeated experiments

How is the meter defined in the metric system now?

distance light travels in 1/(light speed) of a second

dimensionally consistent

equation in which every term has the same dimensions and the arguments of any mathematical functions appearing in the equation are dimensionless

What does it mean for an equation to be dimensionally consistent?

every term has the same dimensions

dimension

expression of the dependence of a physical quantity on the base quantities as a product of powers of symbols representing the base quantities; in general, the dimension of a quantity has the form L a MbT c I d Θ e N f J g for some powers a, b, c, d, e, f, and g

What force acts on the Whirlpool galaxy as well as Earth?

gravity

when S=R, ϴ = 1 radian or 1 rad...

here are 2pi radian in a circle of 360deg

What are the SI base units of length, mass, time, and thermodynamic temperature?

m kg, s, K

SI base units

meter, kilogram, second, kelvin, mole, ampere, candela

What are base quantities?

physical quantity chosen by convention and practical considerations such that all other physical quantities can be expressed as algebraic combinations of them

base quantity

physical quantity chosen by convention and practical considerations such that all other physical quantities can be expressed as algebraic combinations of them

derived quantity

physical quantity defined using algebraic combinations of base quantities