StudySmarter - The all-in-one study app.

4.8 • +11k Ratings

More than 3 Million Downloads

Free

Suggested languages for you:

Americas

Europe

Physical Quantities

A physical quantity is a property of an object, something we can measure with instruments or even by using our senses. Two simple examples of physical quantities are the mass of an object or its temperature. We can measure both with instruments, but we can also sense them using our hands by lifting the object or touching it.Fig. 1 - Mass is a…

Content verified by subject matter experts

Free StudySmarter App with over 20 million students

Explore our app and discover over 50 million learning materials for free.

Physical Quantities

- Astrophysics
- Absolute Magnitude
- Astronomical Objects
- Astronomical Telescopes
- Black Body Radiation
- Classification by Luminosity
- Classification of Stars
- Cosmology
- Doppler Effect
- Exoplanet Detection
- Hertzsprung-Russell Diagrams
- Hubble's Law
- Large Diameter Telescopes
- Quasars
- Radio Telescopes
- Reflecting Telescopes
- Stellar Spectral Classes
- Telescopes
- Atoms and Radioactivity
- Fission and Fusion
- Medical Tracers
- Nuclear Reactors
- Radiotherapy
- Random Nature of Radioactive Decay
- Thickness Monitoring
- Circular Motion and Gravitation
- Applications of Circular Motion
- Centripetal and Centrifugal Force
- Circular Motion and Free-Body Diagrams
- Fundamental Forces
- Gravitational and Electric Forces
- Gravity on Different Planets
- Inertial and Gravitational Mass
- Vector Fields
- Conservation of Energy and Momentum
- Dynamics
- Application of Newton's Second Law
- Buoyancy
- Drag Force
- Dynamic Systems
- Free Body Diagrams
- Normal Force
- Springs Physics
- Superposition of Forces
- Tension
- Electric Charge Field and Potential
- Charge Distribution
- Charged Particle in Uniform Electric Field
- Conservation of Charge
- Electric Field Between Two Parallel Plates
- Electric Field Lines
- Electric Field of Multiple Point Charges
- Electric Force
- Electric Potential Due to Dipole
- Electric Potential due to a Point Charge
- Electrical Systems
- Equipotential Lines
- Electricity
- Ammeter
- Attraction and Repulsion
- Basics of Electricity
- Batteries
- Capacitors in Series and Parallel
- Circuit Schematic
- Circuit Symbols
- Circuits
- Current Density
- Current-Voltage Characteristics
- DC Circuit
- Electric Current
- Electric Generators
- Electric Motor
- Electrical Power
- Electricity Generation
- Emf and Internal Resistance
- Kirchhoff's Junction Rule
- Kirchhoff's Loop Rule
- National Grid Physics
- Ohm's Law
- Potential Difference
- Power Rating
- RC Circuit
- Resistance
- Resistance and Resistivity
- Resistivity
- Resistors in Series and Parallel
- Series and Parallel Circuits
- Simple Circuit
- Static Electricity
- Superconductivity
- Time Constant of RC Circuit
- Transformer
- Voltage Divider
- Voltmeter
- Electricity and Magnetism
- Benjamin Franklin's Kite Experiment
- Changing Magnetic Field
- Circuit Analysis
- Diamagnetic Levitation
- Electric Dipole
- Electric Field Energy
- Magnets
- Oersted's Experiment
- Voltage
- Electromagnetism
- Electrostatics
- Energy Physics
- Big Energy Issues
- Conservative and Non Conservative Forces
- Efficiency in Physics
- Elastic Potential Energy
- Electrical Energy
- Energy and the Environment
- Forms of Energy
- Geothermal Energy
- Gravitational Potential Energy
- Heat Engines
- Heat Transfer Efficiency
- Kinetic Energy
- Mechanical Power
- Potential Energy
- Potential Energy and Energy Conservation
- Pulling Force
- Renewable Energy Sources
- Wind Energy
- Work Energy Principle
- Engineering Physics
- Angular Momentum
- Angular Work and Power
- Engine Cycles
- First Law of Thermodynamics
- Moment of Inertia
- Non-Flow Processes
- PV Diagrams
- Reversed Heat Engines
- Rotational Kinetic Energy
- Second Law and Engines
- Thermodynamics and Engines
- Torque and Angular Acceleration
- Famous Physicists
- Fields in Physics
- Alternating Currents
- Capacitance
- Capacitor Charge
- Capacitor Discharge
- Coulomb's Law
- Dielectric
- Electric Field Strength
- Electric Fields
- Electric Potential
- Electromagnetic Induction
- Energy Stored by a Capacitor
- Equipotential Surface
- Escape Velocity
- Gravitational Field Strength
- Gravitational Fields
- Gravitational Potential
- Magnetic Fields
- Magnetic Flux Density
- Magnetic Flux and Magnetic Flux Linkage
- Moving Charges in a Magnetic Field
- Newton’s Laws
- Operation of a Transformer
- Parallel Plate Capacitor
- Planetary Orbits
- Synchronous Orbits
- Fluids
- Absolute Pressure and Gauge Pressure
- Application of Bernoulli's Equation
- Archimedes' Principle
- Conservation of Energy in Fluids
- Fluid Flow
- Fluid Systems
- Force and Pressure
- Force
- Conservation of Momentum
- Contact Forces
- Elastic Forces
- Force and Motion
- Gravity
- Impact Forces
- Moment Physics
- Moments Levers and Gears
- Moments and Equilibrium
- Pressure
- Resultant Force
- Safety First
- Time Speed and Distance
- Velocity and Acceleration
- Work Done
- Fundamentals of Physics
- Further Mechanics and Thermal Physics
- Bottle Rocket
- Charles law
- Circular Motion
- Diesel Cycle
- Gas Laws
- Heat Transfer
- Heat Transfer Experiments
- Ideal Gas Model
- Ideal Gases
- Kinetic Theory of Gases
- Models of Gas Behaviour
- Newton's Law of Cooling
- Periodic Motion
- Rankine Cycle
- Resonance
- Simple Harmonic Motion
- Simple Harmonic Motion Energy
- Temperature
- Thermal Equilibrium
- Thermal Expansion
- Thermal Physics
- Volume
- Work in Thermodynamics
- Geometrical and Physical Optics
- Kinematics Physics
- Air Resistance
- Angular Kinematic Equations
- Average Velocity and Acceleration
- Displacement, Time and Average Velocity
- Frame of Reference
- Free Falling Object
- Kinematic Equations
- Motion in One Dimension
- Motion in Two Dimensions
- Rotational Motion
- Uniformly Accelerated Motion
- Linear Momentum
- Magnetism
- Ampere force
- Earth's Magnetic Field
- Fleming's Left Hand Rule
- Induced Potential
- Magnetic Forces and Fields
- Motor Effect
- Particles in Magnetic Fields
- Permanent and Induced Magnetism
- Magnetism and Electromagnetic Induction
- Eddy Current
- Faraday's Law
- Induced Currents
- Inductance
- LC Circuit
- Lenz's Law
- Magnetic Field of a Current-Carrying Wire
- Magnetic Flux
- Magnetic Materials
- Monopole vs Dipole
- RL Circuit
- Measurements
- Mechanics and Materials
- Acceleration Due to Gravity
- Bouncing Ball Example
- Bulk Properties of Solids
- Centre of Mass
- Collisions and Momentum Conservation
- Conservation of Energy
- Density
- Elastic Collisions
- Force Energy
- Friction
- Graphs of Motion
- Linear Motion
- Materials
- Materials Energy
- Moments
- Momentum
- Power and Efficiency
- Projectile Motion
- Scalar and Vector
- Terminal Velocity
- Vector Problems
- Work and Energy
- Young's Modulus
- Medical Physics
- Absorption of X-Rays
- CT Scanners
- Defects of Vision
- Defects of Vision and Their Correction
- Diagnostic X-Rays
- Effective Half Life
- Electrocardiography
- Fibre Optics and Endoscopy
- Gamma Camera
- Hearing Defects
- High Energy X-Rays
- Lenses
- Magnetic Resonance Imaging
- Noise Sensitivity
- Non Ionising Imaging
- Physics of Vision
- Physics of the Ear
- Physics of the Eye
- Radioactive Implants
- Radionuclide Imaging Techniques
- Radionuclide Imaging and Therapy
- Structure of the Ear
- Ultrasound Imaging
- X-Ray Image Processing
- X-Ray Imaging
- Modern Physics
- Bohr Model of the Atom
- Disintegration Energy
- Franck Hertz Experiment
- Mass Energy Equivalence
- Nuclear Reaction
- Nucleus Structure
- Quantization of Energy
- Spectral Lines
- The Discovery of the Atom
- Wave Function
- Nuclear Physics
- Alpha Beta and Gamma Radiation
- Binding Energy
- Half Life
- Induced Fission
- Mass and Energy
- Nuclear Instability
- Nuclear Radius
- Radioactive Decay
- Radioactivity
- Rutherford Scattering
- Safety of Nuclear Reactors
- Oscillations
- Energy Time Graph
- Energy in Simple Harmonic Motion
- Hooke's Law
- Kinetic Energy in Simple Harmonic Motion
- Mechanical Energy in Simple Harmonic Motion
- Pendulum
- Period of Pendulum
- Period, Frequency and Amplitude
- Phase Angle
- Physical Pendulum
- Restoring Force
- Simple Pendulum
- Spring-Block Oscillator
- Torsional Pendulum
- Velocity
- Particle Model of Matter
- Physical Quantities and Units
- Converting Units
- Physical Quantities
- SI Prefixes
- Standard Form Physics
- Units Physics
- Use of SI Units
- Physics of Motion
- Acceleration
- Angular Acceleration
- Angular Displacement
- Angular Velocity
- Centrifugal Force
- Centripetal Force
- Displacement
- Equilibrium
- Forces of Nature Physics
- Galileo's Leaning Tower of Pisa Experiment
- Inclined Plane
- Inertia
- Mass in Physics
- Speed Physics
- Static Equilibrium
- Radiation
- Antiparticles
- Antiquark
- Atomic Model
- Classification of Particles
- Collisions of Electrons with Atoms
- Conservation Laws
- Electromagnetic Radiation and Quantum Phenomena
- Isotopes
- Neutron Number
- Particles
- Photons
- Protons
- Quark Physics
- Specific Charge
- The Photoelectric Effect
- Wave-Particle Duality
- Rotational Dynamics
- Angular Impulse
- Angular Kinematics
- Angular Motion and Linear Motion
- Connecting Linear and Rotational Motion
- Orbital Trajectory
- Rotational Equilibrium
- Rotational Inertia
- Satellite Orbits
- Third Law of Kepler
- Scientific Method Physics
- Data Collection
- Data Representation
- Drawing Conclusions
- Equations in Physics
- Uncertainties and Evaluations
- Space Physics
- Thermodynamics
- Heat Radiation
- Thermal Conductivity
- Thermal Efficiency
- Thermodynamic Diagram
- Thermodynamic Force
- Thermodynamic and Kinetic Control
- Torque and Rotational Motion
- Centripetal Acceleration and Centripetal Force
- Conservation of Angular Momentum
- Force and Torque
- Muscle Torque
- Newton's Second Law in Angular Form
- Simple Machines
- Unbalanced Torque
- Translational Dynamics
- Centripetal Force and Velocity
- Critical Speed
- Free Fall and Terminal Velocity
- Gravitational Acceleration
- Kinetic Friction
- Object in Equilibrium
- Orbital Period
- Resistive Force
- Spring Force
- Static Friction
- Turning Points in Physics
- Cathode Rays
- Discovery of the Electron
- Einstein's Theory of Special Relativity
- Electromagnetic Waves
- Electron Microscopes
- Electron Specific Charge
- Length Contraction
- Michelson-Morley Experiment
- Millikan's Experiment
- Newton's and Huygens' Theories of Light
- Photoelectricity
- Relativistic Mass and Energy
- Special Relativity
- Thermionic Electron Emission
- Time Dilation
- Wave Particle Duality of Light
- Waves Physics
- Acoustics
- Applications of Ultrasound
- Applications of Waves
- Diffraction
- Diffraction Gratings
- Doppler Effect in Light
- Earthquake Shock Waves
- Echolocation
- Image Formation by Lenses
- Interference
- Light
- Longitudinal Wave
- Longitudinal and Transverse Waves
- Mirror
- Oscilloscope
- Phase Difference
- Polarisation
- Progressive Waves
- Properties of Waves
- Ray Diagrams
- Ray Tracing Mirrors
- Reflection
- Refraction
- Refraction at a Plane Surface
- Resonance in Sound Waves
- Seismic Waves
- Snell's law
- Spectral Colour
- Standing Waves
- Stationary Waves
- Total Internal Reflection in Optical Fibre
- Transverse Wave
- Ultrasound
- Wave Characteristics
- Wave Speed
- Waves in Communication
- X-rays
- Work Energy and Power
- Conservative Forces and Potential Energy
- Dissipative Force
- Energy Dissipation
- Energy in Pendulum
- Force and Potential Energy
- Force vs. Position Graph
- Orbiting Objects
- Potential Energy Graphs and Motion
- Spring Potential Energy
- Total Mechanical Energy
- Translational Kinetic Energy
- Work Energy Theorem
- Work and Kinetic Energy

Save the explanation now and read when you’ve got time to spare.

SaveLerne mit deinen Freunden und bleibe auf dem richtigen Kurs mit deinen persönlichen Lernstatistiken

Jetzt kostenlos anmeldenNie wieder prokastinieren mit unseren Lernerinnerungen.

Jetzt kostenlos anmeldenA physical quantity is a property of an object, something we can measure with instruments or even by using our senses.

Two simple examples of physical quantities are the mass of an object or its temperature. We can measure both with instruments, but we can also sense them using our hands by lifting the object or touching it.

Fig. 1 - Mass is a physical quantity of an object. Mass per acceleration of gravity gives us the weight of the object.

There is a range of physical properties that we can measure. All these properties are related to an object’s dimensions or its constitution. The seven elemental physical quantities are:

**Mass:**this is the property that tells us how much matter is contained in the object. An object with a larger quantity of matter has a larger mass. Weight is the force exerted over an object’s mass. Mass and weight are often confused. The equation for weight is: \(weight = mass \cdot 9.81m / s ^ 2\).**Length:**this is the property that tells us how long an object is. This property is related to the properties of area and volume.**Time:**this property is related to the flow of events, and it always increases. Like mass, time is one of the properties that cannot be negative. Time tells us the flow of things in the universe.**Electrical charge:**this is a physical quantity that can be positive or negative, only affecting polarity. It causes a force to act upon the matter when placed in an electric field.**Temperature:**this is the property that measures the quantity of heat in a substance or object. Heat is related to the movement of the particles in the object.**Mole:**this is a fixed physical quantity that measures the number of molecules in a substance. The property represents an exact number of particles or molecules equal to \(6.02214076 \cdot 10 ^ {23}\) molecules of the substance.**Luminosity:**this is an energy measure, just like temperature. Luminosity measures the quantity of electromagnetic energy emitted by an object as light per unit time.

People confuse weight and mass all the time. The best way to explain the difference is by using an example featuring a ball.

A ball has a different weight on Mars than it does on Earth. However, the matter that composes the ball remains the same. And if the matter does not change, then neither does the mass.

Weight is the amount of force that gravity exerts on mass; it is force per mass. A scale, therefore, measures the gravitational force that pulls down the mass of an object.

This can also be explained using the gravity force formula that determines the weight of an object:

\[\text{weight} = \text{mass} \cdot \text{gravity}\]

The amount of matter in the ball does not change, so mass is a constant. The main difference is the gravity because gravity on Earth is higher than gravity on Mars:

\[\text{gravity (Earth)} > \text{gravity(Mars)}\]

Therefore, the weight on Earth will be higher than on Mars:

\[\text{mass} \cdot \text{gravity (Earth)} > \text{mass} \cdot \text{gravity(Mars)}\]

Physical quantities have two categories: extensive quantities and intensive quantities. This classification is related to an object’s mass. Extensive quantities depend on an object’s mass or size, while intensive quantities do not.

Mass and electrical charge are examples of extensive physical quantities.

Mass depends on the size of the object. If you have two weights made of steel and one is double the size of the other, the larger one will have double the mass.

Another example concerns electrical charge. If the particles of an object have some electrical charge, their number tells us how much electrical charge the object has. If the object increases its mass, thus increasing its number of particles, the electrical charge will be larger.

Intensive physical quantities do not depend on the object’s mass or size. Simple examples of this are time and temperature.

We can measure the time it takes for two objects of different mass to move from position A to position B. In both cases, time flows in the same way, independent of the composition or size of the objects.

Imagine we have an object with a temperature of 100 Kelvin, which we divide in half. In ideal circumstances where there is no heat transfer, the two halves will each still have the same temperature of 100 K.

Derived physical quantities are the properties of an object that result from two elemental physical quantities. Derived quantities can result from a relationship of the same physical quantity (e.g. area) or by relating two different ones (e.g. velocity). See below for some examples of derived physical quantities.

**Area and volume:** related to length:

\[Area = length \cdot width; \space Volume = length \cdot width \cdot height\]

**Velocity and acceleration:** related to length and time:

\[Velocity = \frac{length}{time}; \space Acceleration = \frac{length}{time^2}\]

**Density:** related to length and mass:

\[Density = \frac{mass}{length^3}\]

**Weight:** related to acceleration and mass (in a planet, acceleration is its gravitational acceleration):

\[Weight = gravity \cdot mass\]

**Pressure:** related to force and length (for pressure, the force can be the weight exerted by an object, and the area over which this force acts is related to length):

\[Pressure = \frac{force}{length^2}\]

Physical quantities have several characteristics related to their properties, some of which are listed below.

- No physical quantity can be less than zero, except for electrical charge and temperature values.
- Some physical quantities can have a value of zero, such as electrical charge or mass. In these cases, the object is electrically neutral (has no charge) or is massless (light).
- Some physical quantities are scalar, which means that they have only a value but no direction. Examples of these quantities are volume, mass, and mole.
- Other physical quantities are vectorial, in which case you need the direction to understand what is happening. Examples of vectorial quantities are velocity and acceleration.

Fig. 2 - A thermometer can display a value below zero.

Temperatures below zero are the result of taking the temperature at which water freezes as a zero (0) value. In Celsius, every temperature below the freezing point of water is negative.

Physical quantities are important because they allow us to describe an object. Objects have a certain mass, a certain length, and a certain amount of atoms. The units are the values of reference we use to measure the properties of objects.

Imagine measuring the weight of two rocks. You can tell by holding them in your hands that one is heavier than the other. However, to determine their precise weight, you need to compare them against a standard value (unit), in this case, the kilogram.

- Physical quantities and units are different. Physical quantities are an object’s physical properties, while units are a reference we use to measure the object’s properties.
- There are two types of physical quantities, elemental quantities and derived quantities. The derived ones are composed of the elemental quantities.
- The seven elemental physical quantities are mass, time, temperature, mole, length, luminosity, and electrical charge.
- Some derived physical quantities are velocity, heat, density, pressure, and momentum.
- Extensive physical quantities depend on the amount of substance or the size of the object.
- Intensive physical quantities do not depend on the amount of substance or the size of the object.
- No physical quantity can be less than zero, except for electrical charge and temperature values.
- Physical quantities are directly related to the units in physics.

A physical quantity is a quantity that is used to describe the properties of an object.

More about Physical Quantities

How would you like to learn this content?

Creating flashcards

Studying with content from your peer

Taking a short quiz

How would you like to learn this content?

Creating flashcards

Studying with content from your peer

Taking a short quiz

Free physics cheat sheet!

Everything you need to know on . A perfect summary so you can easily remember everything.

Be perfectly prepared on time with an individual plan.

Test your knowledge with gamified quizzes.

Create and find flashcards in record time.

Create beautiful notes faster than ever before.

Have all your study materials in one place.

Upload unlimited documents and save them online.

Identify your study strength and weaknesses.

Set individual study goals and earn points reaching them.

Stop procrastinating with our study reminders.

Earn points, unlock badges and level up while studying.

Create flashcards in notes completely automatically.

Create the most beautiful study materials using our templates.

Sign up to highlight and take notes. It’s 100% free.

Save explanations to your personalised space and access them anytime, anywhere!

Sign up with Email Sign up with AppleBy signing up, you agree to the Terms and Conditions and the Privacy Policy of StudySmarter.

Already have an account? Log in