What is the best branch of physics to start with as a beginner?

Classical Mechanics is the best starting point because it deals with tangible everyday phenomena like gravity, speed, and forces, making concepts easy to visualize.

Do I need calculus to learn physics from scratch?

No. Algebra-based physics covers all core principles using basic algebra, geometry, and trigonometry. Calculus is only needed for advanced university-level courses.

What is the fastest way to understand physics formulas?

Focus on the physical relationships between variables rather than memorizing formula symbols.

Can I self-learn physics without a formal teacher?

Yes, using structured roadmaps, online simulations (like PhET), textbooks, and active practice problems allows you to self-learn physics effectively.

What is the difference between heat and temperature?

Temperature measures average kinetic energy of particles, whereas heat is the total thermal energy transferred between objects.

Why does metal feel colder than wood at room temperature?

Metals have higher thermal conductivity, drawing heat away from skin faster than wood even when at identical temperatures.

How is specific heat capacity measured in a lab?

It is measured via electrical calorimetry using the formula c = Pt / (m ΔT) with an immersion heater and insulated vessel.

Can SUVAT equations be used when acceleration is not constant?

No, SUVAT equations strictly apply only when acceleration is uniform and constant. For variable acceleration, calculus techniques must be used.

What is the difference between displacement and distance in SUVAT?

Displacement (s) is a vector measuring overall change in position from start to end point, while distance is a scalar measuring total path length traveled.

Why is acceleration negative when an object slows down?

Deceleration means final velocity is less than initial velocity (v < u), resulting in a negative rate of change for velocity relative to the positive direction of motion.

What value of g should I use for free fall SUVAT problems?

Standard gravity is approximately 9.81 m/s², though many physics courses round to 9.8 m/s² or 10 m/s² for easier calculation.

How do SUVAT equations apply to 2D projectile motion?

SUVAT equations apply independently to the vertical axis with acceleration a = -g, while the horizontal axis experiences zero acceleration (a = 0).

Why can't objects with mass travel at the speed of light?

As velocity approaches c, the Lorentz factor approaches infinity, requiring an infinite amount of energy to accelerate any massive object to light speed.

What is the twin paradox in special relativity?

The twin paradox compares a traveling twin and an Earth-bound twin. The space traveler returns younger due to time dilation caused by relativistic speeds and frame-changing acceleration.

Does length contraction affect dimensions perpendicular to motion?

No, length contraction occurs exclusively along the direction of relative travel. Perpendicular axes retain their original proper dimensions.

How does special relativity differ from general relativity?

Special relativity addresses flat spacetime and non-accelerating inertial frames, while general relativity incorporates gravitational acceleration and curved spacetime.

What is the difference between centripetal force and centrifugal force?

Centripetal force is a real net inward force causing circular path trajectory. Centrifugal force is a fictitious outward effect felt in rotating non-inertial reference frames due to inertia.

Why does a vehicle slide outward on an icy curve?

Static friction provides required centripetal force on flat turns. Ice lowers available friction below required mv^2/r, causing inertia to move the vehicle tangentially outward.

Is work done by a centripetal force in uniform circular motion?

No work is done because centripetal force acts strictly perpendicular (90 degrees) to displacement at all points along the circular path.

How does changing velocity affect centripetal acceleration?

Centripetal acceleration varies quadratically with speed (v^2/r). Doubling velocity quadruples inward acceleration requirements.

Is mechanical energy conserved during all collisions?

Total energy is conserved in every collision. However, kinetic energy is only conserved in perfectly elastic collisions. In inelastic collisions, kinetic energy converts into heat, deformation, and sound.

Can potential energy have a negative value?

Yes, potential energy can be negative if the object lies below your chosen zero reference level. Only relative changes in potential energy matter in calculations.

What is the relationship between net work and energy?

Work is the mechanism of energy transfer. The net work done on an object equals its change in kinetic energy according to the Work-Energy Theorem.

Physics Glossary & Terminology

Physics Glossary — Physics Terms & Definitions

Clear physics definitions for essential terms, formulas, and concepts. Browse our A-Z physics dictionary for quick exam revision and homework reference.

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Essential Physics Terms Defined

Fundamental physics terms and definitions explained in clear, simple language.

Physics Terms A-Z Index

Acceleration

Rate of change of velocity. a=(v-u)/t. Measured in m/s2. A vector quantity.

Amplitude

Maximum displacement from equilibrium. Determines wave energy and intensity.

Centripetal Force

Net force toward the centre of circular motion. F=mv2/r. Not a new force.

Conservation of Energy

Total energy of an isolated system is constant. Energy converts between forms, never lost.

Diffraction

Spreading of waves around obstacles. Greatest when wavelength equals gap size.

Displacement

Change in position (start to finish, straight line). Vector, measured in metres.

Electric Field

Region where a charge experiences a force. E=F/q, measured in N/C or V/m.

Entropy

Measure of disorder. Second Law: entropy of an isolated system always increases.

Frequency

Oscillations per second. f=1/T. Measured in Hertz (Hz).

Gravitational PE

Energy due to position. GPE=mgh. Reference level is arbitrary.

Impulse

Change in momentum. J=Fxt=Dp. Measured in N*s or kg*m/s.

Inertia

Resistance to change in motion. Measured by mass.

Interference

Superposition of waves. Constructive: crests align. Destructive: crest meets trough.

Kinetic Energy

Energy of motion. KE=(1/2)mv2. Doubling speed quadruples KE.

Momentum

p=mv. Vector, kg*m/s. Conserved in closed systems.

Newton 1st Law

Object stays at rest or constant velocity unless net force acts. Law of inertia.

Newton 2nd Law

F=ma. Net force = mass times acceleration. Both are vectors.

Newton 3rd Law

Every action has equal and opposite reaction on a different object.

Ohm's Law

V=IR. Voltage = current times resistance. Valid at constant temperature.

Period

Time for one complete oscillation. T=1/f. Measured in seconds.

Photoelectric Effect

Electron emission by light of sufficient frequency. Explained by photon energy E=hf.

Power

Rate of energy transfer. P=W/t=IV. Measured in Watts (W).

Projectile Motion

Motion under gravity: horizontal (constant v) and vertical (constant g=9.81m/s2) are independent.

Refraction

Wave direction change at a boundary. Snell Law: n1*sinO1=n2*sinO2.

Scalar

Quantity with magnitude only. Examples: speed, mass, temperature, energy.

Special Relativity

Laws of physics identical in all inertial frames. Speed of light constant. Leads to E=mc2.

Specific Heat Capacity

Energy to raise 1kg by 1K. Q=mcDT. Water: c=4186 J/kg/K.

Torque

Rotational force. tau=Fr*sinO. Measured in Newton-metres (N*m).

Transverse Wave

Particles oscillate perpendicular to wave travel. Examples: light, radio waves.

Velocity

Rate of change of displacement. v=Ds/Dt. Vector, m/s.

Wavelength

Distance between identical wave points (crest to crest). Symbol lambda. From v=f*lambda.

Work

W=Fs*cosO. Work done only when force has component along displacement. Joules.

Frequently Asked Questions About Physics Terms

Quick answers regarding our physics glossary, definitions, and key concepts.

What is included in this physics glossary?

This online physics glossary provides concise definitions and key formulas for essential physics terms across mechanics, waves, thermodynamics, electricity, and modern physics.

Are these physics definitions suitable for high school and O-Level revision?

Yes, all definitions are formatted according to standard curriculum guidelines, making them ideal for GCSE, O-Level, A-Level, and AP Physics exam review.