Physics unit 1

Absolute Error

Absolute Error

the absolute value of the difference between an observed value of a quantity and the true value

Accuracy

the degree to which the result of a measurement, calculation, or specification conforms to the correct value or a standard.

Circumference

the enclosing boundary of a curved geometric figure, especially a circle.

Cosine

the trigonometric function that is equal to the ratio of the side adjacent to an acute angle (in a right-angled triangle) to the hypotenuse.

Dependent Variable

a variable (often denoted by y ) whose value depends on that of another.

Derived Unit

A derived unit is a unit of measurement in the International System of Units (SI) that is derived from one or more of the seven base units.

Diameter

a straight line passing from side to side through the center of a body or figure, especially a circle or sphere.

Dimensional Analysis

analysis using the fact that physical quantities added to or equated with each other must be expressed in terms of the same fundamental quantities (such as mass, length, or time) for inferences to be made about the relations between them.

Direct Relationship

A direct relationship means that both variables increase together or both decrease together. In a direct relationship, Y increases when X increases. On a graph, a direct relationship always has a positive slope.

Direct Square Relationship

y=kx^2

Energy

power derived from the utilization of physical or chemical resources, especially to provide light and heat or to work machines.

Fundamental Units

one of a set of unrelated units of measurement, which are arbitrarily defined and from which other units are derived. For example, in the SI system the fundamental units are the meter, kilogram, and second.

Horizontal Component of a Vector

The 𝑥 -component, or the horizontal component, of a vector is the size of the vector in the 𝑥 -direction.

Hypothesis

a proposed explanation for a phenomenon

Independent Variable

a variable (often denoted by x ) whose variation does not depend on that of another.

Inverse Relationship

a situation where if one variable increases, the other tends to decrease

Inverse Square Relationship

that a specified physical quantity is inversely proportional to the square of another

Line or Curve of Best Fit

a straight line that minimizes the distance between it and some data. The line of best fit is used to express a relationship in a scatter plot of different data points.

Linear Relationship

a statistical term used to describe a straight-line relationship between two variables

Mass

a measurement of how much matter is in an object

Matter

a substance made up of various types of particles that occupies physical space and has inertia

Measurement

the determination of the size or magnitude of something

Metric System

a system used for measuring distance, length, volume, weight and temperature. It is based on three basic units with which we can measure almost everything in the world

Percent Error

the difference between estimated value and the actual value in comparison to the actual value and is expressed as a percentage.

Physics

the branch of science concerned with the nature and properties of matter and energy. The subject matter of physics, distinguished from that of chemistry and biology, includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms.

Precision

how close measurements of the same item are to each other

Pythagorean Theorem

a^2 + b^2 = c^2

Quadratic Relationship

a mathematical relation between two variables that follows the form of a quadratic equation

Relative Precision

the ratio of a measurement's precision and the measurement itself.

Rest

An object is said to be at rest if it does not change its position with respect to its surroundings with time.

Scalar Quantity

quantities that are fully described by a magnitude (or numerical value) alone.

Scientific Fact

an observation that's been confirmed so many times that scientists can, for all intents and purposes, accept it as "true."

Scientific Law

a statement that describes an observable occurrence in nature that appears to always be true

Scientific Method

a method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.

Scientific Notation

a way of writing very large or very small numbers. A number is written in scientific notation when a number between 1 and 10 is multiplied by a power of 10.

Scientific Theory

a structured explanation to explain a group of facts or phenomena in the natural world that often incorporates a scientific hypothesis and scientific laws

Significant Digits

each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first nonzero digit

Sine

the trigonometric function that is equal to the ratio of the side opposite a given angle (in a right triangle) to the hypotenuse.

Slope

the ratio of the change in the y-axis to the change in the x-axis

Square Root Relationship

y = k√x

Stop

when velocity = 0

Unit

standards for measurement of physical quantities that need clear definitions to be useful.

Vector Quantity

The physical quantities for which both magnitude and direction are defined distinctly

Vertical Component of a Vector

The 𝑦 -component, or the vertical component, of a vector is the size of the vector in the 𝑦 -direction.

Weight

Weight is the Gravitational force with which the Earth attracts the masses towards its center.

y = mx + b

slope formula

y = ax2 + bx +c

parabola formula

Physics is fundamental

is necessary to understand all other sciences.

Classical physics

is the physics studied from the Renaissance age to the 19th century

Modern physics

is discoveries made from the start of the 20th century.

Classical physics is based on the following conditions

1. Matter must be moving at speeds less than about 1% of the speed of light, 2. The object studies must be large enough to see with the naked eye, 3. Only weak gravity, like that generated by the Earth, can be involved.

Modern physics is based on

the theory of relativity and quantum mechanics. Relativity

Quantum mechanics

deals with the very small and the very fast.

Mathematics is the tool we use to communicate physics.

Physics is the study of

matter and energy to gain a deeper understanding of our universe.

Kilo

10^3, k

Centi

10^-2, c

Milli

10^-3, m

Micro

10^-6, 𝛍

Meter

length

Kilogram

mass

Second

time

Ampere

current

Kelvin

temperature

Mole

amount of substance

Candela

luminous intensity

Length

standard unit is the meter, the meter was once considered the distance between the North Pole and the equator, a bar in a lab in France was used to measure a meter, today 1 m= distance traveled by light in a vacuum 1/299192458 sec

Mass

quantity to measure amounts of matter, standard- mass of a prototype (platinum-iridium cylinder in France)

Time

second 1/86,400 of a solar day, radiation frequency of the cesium-133 atom

Volume

measured by liters or cm3, 1 Liter = 1000 cm3

Fundamental Units

Kilograms, meters (can be measured with a tool)

Derived Units

Combination of fundamental units

Length

l (d), meter: m

Time

t, second: s

Mass

m, kilogram: kg

electric charge

q, coulomb: C

Temperature

T, kelvin: K

amount of substance

n, mole: mol

luminous intensity

l, candela: cd

Accuracy

the degree to which the result of a measurement, calculation, or specification conforms to the correct value or a standard.

Precision

refinement in a measurement, calculation, or specification, especially as represented by the number of digits given.

Observational error

is the difference between a measured quantity and its true value (remember we may not know what its true value is), two types

Random error

naturally occurring errors that are to be expected with any experiment, variability between different measurements, when your average is closer to the actual value

Systematic error

caused by a mis-calibrated instrument that affects all measurement, skews your measurement away from the true value in a specific direction (bias- your data is skewed in standardized ways that hide the true value

Absolute Error

the amount of error in your measurements/the difference between the measured value and “true” value. (Δx) = xi – x

Absolute Error of a measuring tool

The absolute error of any measuring tool is determined by the smallest spacing on a tool.

Relative Precision of a Tool

Absolute Error of the ToolSmallest Measurement of Data x 100

Relative Precision of a Data Set

Range of DataAverage x 100

Absolute Error

accepted reading-observed reading

Relative Error

Accepted Reading-Observed ReadingAccepted Reading

Percent Error

Accepted Reading-Observed ReadingAccepted Readingx 100

Graphing

helps us to visually analyze data

Linear relationship

y = kx

Inverse relationship

y = k/x

Inverse square relationship

y = k/x2

Power relationship

y = kx2

Square Root Relationship

y = k√x

Slope

change in y divided by the change in x

Interpolation

is a type of estimation, a method of constructing new data points within the range of a discrete set of known data points.

Extrapolation

is a type of estimation, beyond the original observation range, of the value of a variable on the basis of its relationship with another variable.