DBS10042 Engineering Science: Comprehensive Review

Vocabulary flashcards covering core physics concepts, laws, formulas, and terminology from DBS10042 Engineering Science.

Physical Quantity

A physical property of a phenomenon, body, or substance that can be quantified by measurement.

Base Quantities

Fundamental physical quantities on the basis of which other quantities can be expressed, consisting of seven primary base units including length ($\text{m}$), mass ($\text{kg}$), time ($\text{s}$), electric current ($\text{A}$), temperature ($\text{K}$), and luminous intensity ($\text{cd}$).

Derived Quantities

Quantities that are derived through the multiplication, division, or both, of base quantities (such as area in $\text{m}^2$, volume in $\text{m}^3$, velocity in $\text{m/s}$, and acceleration in $\text{m/s}^2$).

Scalar Quantities

Physical quantities that are completely described by a magnitude (numerical value and unit) alone, with no associated direction (e.g., distance, speed, mass, volume, temperature, density, energy, power, work).

Vector Quantities

Physical quantities that require both a magnitude and a specific direction to be fully described (e.g., displacement, velocity, acceleration, force, momentum, and magnetic field).

International System of Units (SI Unit)

The modern form of the metric system and the most widely used measurement system worldwide, comprising a coherent framework built upon seven base units.

Accuracy

The closeness of an experimental measurement to the true or actual value of the physical quantity being measured.

Consistency

The repeatability of measurement results under the same conditions, representing an instrument's ability to produce consistent readings when measuring the same quantity repeatedly.

Sensitivity

The ability of a measuring instrument to detect and respond to very small changes in the quantity being measured.

Random Error

Unpredictable variations during measurement caused by unknown and uncontrolled environmental changes, which cause readings to scatter around a mean value and can be minimized by repeating measurements and averaging.

Systematic Error

A consistent bias in one direction (consistently too high or consistently too low) originating from flaws in the measuring instrument or experimental technique, reducible through calibration and zero-error corrections.

Zero Error

A condition where a measuring instrument provides a non-zero reading when the actual quantity being measured is zero; it can be positive or negative and must be subtracted from observed readings.

Linear Motion

Motion occurring along a straight line that can be described mathematically using a single spatial dimension.

Uniform Motion

Movement along a straight line at a constant speed with zero acceleration.

Non-Uniform Motion

Motion that involves changes in speed, changes in direction, or simultaneous changes in both.

Distance

The actual length of the path (line or curve) traced out by an object moving through space; it is a scalar quantity measured in metres ($\text{m}$).

Displacement

The shortest straight-line distance measured between an initial position and a final position in a specified direction; it is a vector quantity measured in metres ($\text{m}$).

Speed

The rate of change of distance traveled with respect to time ($v = \frac{d}{t}$); a scalar quantity measured in metres per second ($\text{m/s}$).

Velocity

The rate of change of displacement with respect to time ($V = \frac{s}{t}$); a vector quantity measured in metres per second ($\text{m/s}$).

Acceleration

The rate of change of velocity over time ($a = \frac{v - u}{t}$); a vector quantity measured in metres per second squared ($\text{m/s}^2$).

Deceleration

The negative rate of change of velocity when a moving object is slowing down; expressed mathematically as a negative acceleration value in metres per second squared ($\text{m/s}^2$).

Velocity-Time Graph Principles

On a plot of velocity versus time, the gradient of the curve represents acceleration (or deceleration), while the area beneath the curve represents the total distance or displacement traveled.

Force

Any influence (intuitively described as a push or a pull) that causes an object to change its speed, direction of motion, or geometric shape; a vector quantity measured in Newtons ($\text{N}$).

Net Force

The non-zero resultant or unbalanced force acting upon a body when all individual applied forces do not cancel out, causing acceleration in the direction of the net force.

Newton's First Law of Motion

The principle that an object remains at rest or continues to move with constant velocity along a straight path unless acted upon by an external net unbalanced force ($\sum F_{\text{net}} = 0$).

Newton's Second Law of Motion

The principle that the acceleration of an object is directly proportional to the net force applied, acts in the direction of the net force, and is inversely proportional to the mass of the object ($F = ma$).

Newton's Third Law of Motion

The law stating that for every applied action force, there exists an equal in magnitude and opposite in direction reaction force ($F_{\text{action}} = F_{\text{reaction}}$), demonstrating that forces always occur in matched pairs.

Mass

The intrinsic measure of the quantity of matter contained within a body; a constant scalar quantity that does not vary with location, measured in kilograms ($\text{kg}$).

Weight

The gravitational force exerted downward on an object's mass ($W = mg$); a vector quantity measured in Newtons ($\text{N}$) that varies according to local gravitational acceleration.

Forces in Equilibrium

The mechanical state of a body where the vector sum of all forces and the sum of all moments acting upon it equal zero ($\sum F = 0$ and $\sum M = 0$), resulting in zero net acceleration.

Resultant Force Resolution Method

A technique where forces are decomposed into orthogonal Cartesian components ($F_x = F\cos(\theta)$ and $F_y = F\sin(\theta)$), giving a total resultant magnitude $F_R = \sqrt{(\sum F_x)^2 + (\sum F_y)^2}$ and direction $\theta = \tan^{-1}\left(\frac{\sum F_y}{\sum F_x}\right)$.

Moment of Force

The turning effect of a force about a specific pivot or point of rotation, defined as the product of the force and the perpendicular distance from the pivot to the line of action ($M = F \times d$), measured in Newton metres ($\text{N}\cdot\text{m}$).

Principle of Moments

The law stating that for a body in rotational equilibrium, the total sum of clockwise moments about any pivot must equal the total sum of anticlockwise moments ($\sum M_{\text{clockwise}} = \sum M_{\text{anticlockwise}}$).

Work

The product of the magnitude of an applied force and the displacement moved in the direction of the force ($W = Fs$ or $W = Fd\cos(\theta)$), measured in Joules ($\text{J}$) or Newton metres ($\text{N}\cdot\text{m}$).

Energy

The capacity or potential of a physical system to perform work; a scalar derived quantity measured in Joules ($\text{J}$).

Kinetic Energy

The mechanical energy an object possesses due to its motion, directly dependent upon the object's mass and the square of its speed ($KE = \frac{1}{2}mv^2$), measured in Joules ($\text{J}$).

Gravitational Potential Energy

The energy stored within an object as a result of its vertical elevation or position relative to a reference datum ($PE = mgh$), measured in Joules ($\text{J}$).

Principle of Conservation of Energy

The fundamental law stating that energy cannot be created or destroyed; it can only be transformed from one form to another, meaning the total energy of an isolated system remains constant.

Power

The rate at which work is performed or the rate at which energy is transferred over time ($P = \frac{W}{t} = F \times v$), measured in Watts ($\text{W}$) or Joules per second ($\text{J/s}$).

Energy Efficiency (Mechanical System)

The percentage ratio of useful output energy (or power/work) produced by a machine relative to the total input energy (or power/work) supplied ($\eta = \frac{\text{Useful Output}}{\text{Total Input}} \times 100\%$).

Renewable Energy

Energy collected from natural resources that are naturally replenished on a human timescale, including solar, wind, hydro, wave, tidal, and geothermal sources.

Non-Renewable Energy

Energy obtained from finite natural resources that deplete with use and cannot be regenerated within human lifetimes, primarily fossil fuels such as coal, petroleum, and natural gas formed during the Carboniferous Period.

Material Density

The mass per unit volume of a given substance ($\rho = \frac{m}{V}$); an intensive scalar property measured in kilograms per cubic metre ($\text{kg/m}^3$).

Relative Density

The dimensionless ratio of the density of a substance to the density of pure water at standard conditions ($\rho_{\text{relative}} = \frac{\rho_{\text{substance}}}{\rho_{\text{water}}}$, where $\rho_{\text{water}} = 1000\,\text{kg/m}^3$).

Pressure

The normal (perpendicular) force exerted per unit surface area over which the force is distributed ($P = \frac{F}{A}$), measured in Pascals ($\text{Pa}$) or Newtons per square metre ($\text{N/m}^2$).

Pressure in Liquid (Hydrostatic Pressure)

The pressure acting equally in all directions at depth $h$ within a liquid of uniform density, independent of surface area or container shape ($P = \rho gh$).

Pascal's Principle

The principle stating that pressure applied to an enclosed, confined fluid is transmitted equally and undiminished in all directions throughout the entire fluid ($P_{\text{input}} = P_{\text{output}}$, or $\frac{F_1}{A_1} = \frac{F_2}{A_2}$).

Archimedes' Principle

The principle stating that when an object is wholly or partially immersed in a fluid, it experiences an upward buoyant force equal to the weight of the fluid displaced by the object ($F_b = \rho_f V_d g$).

Buoyant Force ($F_b$)

The net upward force exerted by a fluid upon an immersed body, equal to the weight of displaced liquid ($F_b = \rho_f V_d g$) and calculated as the difference between actual weight in air and apparent weight in fluid ($F_b = W - W_{\text{app}}$).

Apparent Weight ($W_{\text{app}}$)

The effective downward force of an object measured while immersed in a fluid, equal to its true weight in air minus the upward buoyant force ($W_{\text{app}} = W - F_b$).

Floating Condition

The equilibrium state for an object floating at rest on a fluid surface where the upward buoyant force precisely balances the total downward gravitational weight of the object ($F_b = W = mg$).

Temperature

A fundamental measure of the degree of hotness or coldness of an object, reflecting thermal state; an SI base quantity measured in Kelvin ($\text{K}$) or degrees Celsius ($^\circ\text{C}$).

Heat

Thermal energy in transit from a body of higher temperature to a body of lower temperature; a derived quantity measured in Joules ($\text{J}$) or calories ($\text{cal}$).

Conduction

The transfer of thermal energy through a material medium by direct physical contact between adjacent microscopic particles without macroscopic motion of the material.

Convection

The transfer of thermal energy within a fluid (liquid or gas) caused by the physical circulation and bulk motion of the fluid itself driven by density differentials.

Radiation

The transfer of thermal energy in the form of electromagnetic waves (rays) through space that requires no physical or material medium to propagate.

Heat Capacity ($C$)

The amount of heat energy required to raise the temperature of an entire body or sample by $1\,^\circ\text{C}$ or $1\,\text{K}$ ($C = \frac{Q}{\Delta\theta}$), measured in $\text{J/}^\circ\text{C}$ or $\text{J/K}$.

Specific Heat Capacity ($c$)

The quantity of heat energy required to raise the temperature of a unit mass ($1\,\text{kg}$) of a substance by $1\,^\circ\text{C}$ or $1\,\text{K}$ ($c = \frac{Q}{m\Delta\theta}$), measured in $\text{J/(kg}\cdot^\circ\text{C)}$ or $\text{J/(kg}\cdot\text{K)}$.

Latent Heat ($L$)

The amount of heat energy absorbed or released by a substance during an isothermal change of physical state (fusion or vaporisation) without any change in temperature ($Q = mL$), measured in $\text{J/kg}$.

Thermal Equilibrium

The steady state achieved when two or more substances in thermal contact reach identical temperatures, resulting in zero net thermal energy transfer between them ($Q_{\text{lost}} = Q_{\text{gained}}$).