Physics Handbook – Units, Measurements & Motion in a Straight Line

Vocabulary flashcards covering essential terms and definitions from Units & Measurements (Unit-1) and Motion in a Straight Line (Unit-2).

Pascal (Pa)

The SI unit of pressure, equal to one newton per square metre (N m⁻²).

Plane Angle

A dimensionless quantity defined as the ratio of the length of an arc to its radius.

Radian

The SI unit of plane angle; corresponds to an arc length equal to the radius of the circle.

Candela (cd)

The SI base unit of luminous intensity of light.

Coefficient of Viscosity

Measure of a fluid’s resistance to flow with dimensional formula [M L⁻¹ T⁻¹].

Significant Figures

Digits in a number that are certainly known plus one uncertain digit, indicating measurement precision.

Angular Displacement

A dimensionless physical quantity representing angle moved; has no fundamental dimensions.

Torque Dimensions

[M L² T⁻²] – same fundamental dimensions as work or energy.

Angular Momentum Dimensions

[M L² T⁻¹] – identical to Planck’s constant dimensions.

Principle of Homogeneity

States that all additive terms in an equation must have identical dimensions.

Dimensional Formula

Expression showing powers of fundamental quantities (M, L, T, etc.) required to represent a physical quantity.

Dimensional Analysis

Method using dimensions to convert units, check equation correctness or derive relations between quantities.

Fundamental Physical Quantity

A basic measurable quantity independent of other quantities (e.g., length, mass, time).

Derived Physical Quantity

Quantity expressed in terms of fundamental quantities (e.g., velocity = length / time).

Solid Angle

A dimensionless measure of a cone’s spread in space; SI unit is the steradian (sr).

Steradian (sr)

The SI unit of solid angle.

Universal Gravitational Constant (G)

Physical constant with negative dimension in mass: [M⁻¹ L³ T⁻²].

Orbital Velocity (√gR)

Velocity required for a body to orbit Earth at surface level; proportional to square root of g times Earth’s radius.

Work (P V)

Product of pressure and volume, resulting in energy measured in joules.

Pressure (N m⁻²)

Force per unit area; also called Pascal.

Kinematics

Branch of mechanics that describes motion without regard to its causes.

Displacement

Shortest vector from initial to final position of an object; can be zero even with non-zero distance.

Average Speed

Total path length divided by total time taken.

Average Velocity

Net displacement divided by total time interval.

Instantaneous Velocity

Velocity of an object at a specific instant, equal to derivative dx/dt.

Uniform Motion

Motion with constant velocity; equal distances in equal time intervals.

Acceleration

Rate of change of velocity with time; a = Δv/Δt.

Uniform Acceleration

Constant acceleration throughout a motion.

Acceleration due to Gravity (g)

Constant acceleration experienced by freely falling bodies near Earth, approximately 9.8 m s⁻² downward.

Kinematic Equation: v = u + at

Relates final velocity v to initial velocity u, acceleration a and time t for constant a.

Kinematic Equation: s = ut + ½at²

Gives displacement s under constant acceleration a after time t.

Kinematic Equation: v² – u² = 2as

Connects velocities, acceleration and displacement without explicit time.

Area under v-t Curve

Represents displacement of an object over the time interval considered.

Slope of s-t Graph

Gives instantaneous velocity at any point.

Slope of v-t Graph

Represents acceleration of the object.

Free-Fall Distance Ratio (1 : 3 : 5)

Distances covered in successive seconds by a freely falling body starting from rest increase in the ratio 1:3:5.

Uniform Velocity (Zero Acceleration)

If velocity is constant, acceleration equals zero.

Dimensionless Constant

A pure number without units, such as K in orbital period expressions.

Rules: Significant Figures (Multiplication/Division)

Result retains as many significant figures as the operand with the least significant figures.

Rules: Significant Figures (Addition/Subtraction)

Result retains as many decimal places as the term with the least decimal places.