Physics Lecture on Physical Quantities and Measurements

These flashcards cover essential vocabulary terms related to physical quantities, measurements, and their systems in physics.

Physical Quantities

All quantities that can be measured, such as time, length, mass, force, work done, etc.

Fundamental Quantities

A set of physical quantities that are independent and can be expressed in terms of these quantities, such as mass, time, length, current, temperature, luminous intensity, and amount of substance.

Derived Physical Quantities

Physical quantities that can be expressed in terms of fundamental physical quantities, for example, speed calculated as distance/time.

Measurement

The comparison of a quantity with a standard of the same physical quantity.

Units

Standard magnitudes of the same physical quantity used for measurement, such as second, meter, kilogram.

FPS System

British Engineering system where length, mass and time are fundamental quantities, with units foot, pound, and second.

CGS System

Gaussian system where length, mass, and time are fundamental quantities, with respective units centimeter, gram, and second.

MKS System

Metric system where length, mass, and time are fundamental quantities with units meter, kilogram, and second respectively.

SI Units

International system of units including seven base units for various physical quantities.

Radian

The angle subtended at the center of a circle by an arc equal in length to the radius of the circle.

Steradian

The solid angle subtended at the center of a sphere by a surface area equal to the square of the radius of the sphere.

Dimensional Formula

An expression representing a physical quantity in terms of base quantities, for example, force expressed as [M^1L^1T^-2].

Dimensional Equation

An equation that equates the dimensions of a physical quantity to its dimensional formula.

Principle of Homogeneity

States dimensions on both sides of an equation must be the same.

Specific Heat Capacity

Amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius.

Statistical Error

Variance in measured values due to random fluctuations affecting accuracy and precision.

Zero Error

Error indicated when the measuring scale does not start from zero.

Significant Figures

Digits in a measurement that communicate the precision of the measurement.

Least Count

The smallest value that can be measured by an instrument.

Density

Mass per unit volume of a substance.

Cohesion

The attraction between molecules of the same substance.