General Physics 1: Measurements, Units, and Errors

These flashcards cover fundamental concepts of physical quantities, SI and English units, scientific notation, significant figures, measurement errors, uncertainty, and the distinction between scalar and vector quantities as presented in the lecture notes.

Physical Quantity

Anything that can be measured and expressed using a number and a unit.

SI Base Units

The International system of Unit (SI) is the standard system used worldwide for measurements.

Meter ($m$)

The SI base unit for length.

Kilogram ($kg$)

The SI base unit for mass.

Second ($s$)

The SI base unit for time.

Kelvin ($k$)

The SI base unit for temperature.

Ampere ($A$)

The SI base unit for electric current.

Mole ($mol$)

The SI base unit for the amount of substance.

Candela ($cd$)

The SI base unit for luminous intensity.

Derived Units

Units formed by combining SI Base Units, such as area ($m^2$), volume ($m^3$), speed ($m/s$), acceleration ($m/s^2$), and density ($kg/m^3$).

Scientific Notation

A way to write very large or very small numbers in the form $a \times 10^n$, where $a$ is a number from $1$ to $9.99$ and $n$ is the exponent.

Metric Prefix: Kilo ($k$)

A prefix representing a value of $10^3$.

Metric Prefix: Milli ($m$)

A prefix representing a value of $10^{-3}$.

Metric Prefix: Micro ($\mu$)

A prefix representing a value of $10^{-6}$.

Significant Figures

Rules for counting digits in measurements: all non-zero digits are significant, zeros between non-zeros are significant, leading zeros are not, and trailing zeros after a decimal are significant.

Accuracy

Refers to how close a measured value is to the true, accepted, or theoretical value of a physical quantity.

Precision

Refers to how close repeated measurements are to each other, regardless of the true value.

Percent Error

A quantitative expression of accuracy calculated as $\frac{\text{Experimental value} - \text{True value}}{\text{True Value}} \times 100\%$.

Random Error

Unpredictable fluctuations in readings caused by environmental changes or operator inconsistency; affects precision.

Systematic Error

Consistent, repeatable inaccuracies from faulty equipment, improper calibration, or observer bias; affects accuracy.

Parallax Error

An error occurring when the apparent position of an object changes because the observer is looking at a scale from an angle rather than perpendicularly.

Measurement Uncertainty

A quantitative estimate of the range within which the true value of a measurement is expected to lie.

Absolute Uncertainty ($\Delta x$)

The uncertainty calculated as $Range \div 2$, where Range is the maximum value minus the minimum value.

Slope ($m$)

The rate of change of the variable on the vertical axis ($y$-axis) with respect to the variable on the horizontal axis ($x$-axis), calculated as $\frac{y_2 - y_1}{x_2 - x_1}$.

Scalar Quantities

Physical quantities described completely by magnitude and a unit, with no sense of direction (e.g., mass, time, temperature).

Vector Quantities

Physical quantities that require both magnitude and a specific direction to be fully defined (e.g., displacement, velocity, force).

Displacement

A vector quantity indicating where you are relative to your starting point.

Velocity

A vector quantity representing speed with a specific direction.