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 Formulas Library & Key Equations

Physics Formulas & Equations Library — Every Formula You Need

Every physics formula and equation organized by topic — with clear formulas, names, definitions, and SI units. Bookmark this guide for quick exam reference.

Essential Mechanics & Machinery Formulas

Calculate force, mass, acceleration, and mechanical advantage using core physics equations. Master Newton’s laws of motion, net force equations, tension force, and work-energy formulas for quick problem-solving. These fundamental machinery formulas help you easily determine normal force, spring constants, friction, and kinetic energy in real-world physics problems

Mechanics

F = ma

Newton 2nd Law

Net force = mass × acceleration. N.

v = u + at

SUVAT (1)

Final velocity with constant acceleration. m/s.

s = ut + ½at²

SUVAT (2)

Displacement with initial velocity. m.

KE = ½mv²

Kinetic Energy

Energy of motion. J.

PE = mgh

Potential Energy

Gravitational PE. J.

p = mv

Momentum

Mass × velocity (vector). kg·m/s.

W = Fs cosθ

Work Done

Force × displacement × cosθ. J.

P = W/t

Power

Work per unit time. W.

Wave Motion, Frequency & Wavelength Formulas

Master wave mechanics with essential wave speed equations, frequency formulas, and wavelength calculations. Explore core principles governing transverse waves, longitudinal waves, standing waves, and wave interference. Easily calculate wave frequency from wavelength and understand the fundamental frequency and wavelength relationship for sound, light, and electromagnetic waves.

Waves

v = fλ

Wave Equation

Speed = frequency × wavelength. m/s.

f = 1/T

Frequency

Cycles per second. Hz.

T = 1/f

Period

Time for one cycle. s.

n1 sinθ1 = n2 sinθ2

Snell Law

Law of refraction. Dimensionless.

I = P/A

Wave Intensity

Power per unit area. W/m².

E = hf

Photon Energy

Planck constant × frequency. J.

Electricity, Circuits & Electromagnetism Formulas

Master electrical circuit calculations using Ohm’s law formula ( $V = IR$ ), power physics equations, and resistance principles. Easily calculate magnetic force equations, magnetic field formulas, electrostatic forces, and Coulomb force formulas. Use these essential physics formulas to understand Lenz’s law, magnetic flux, and current flow in both basic and advanced electrical circuits.

Electricity

V = IR

Ohm Law

Voltage = current × resistance. V.

P = IV

Electrical Power

Voltage × current. W.

F = kq1q2/r²

Coulomb Law

Force between two point charges. N.

I = Q/t

Current

Charge flow per unit time. A.

E = F/q

Electric Field

Force per unit charge. N/C.

EMF = NΔΦ/Δt

Faraday Law

Induced EMF from changing flux. V.

Thermodynamics, Heat Capacity & Thermal Physics Formulas

Master heat transfer and thermal energy calculations using the first law of thermodynamics and second law of thermodynamics equations. Easily apply the specific heat capacity formula, heat capacity units, and thermal expansion formulas to calculate heat conduction, convection, and radiation. Use these essential physics formulas to determine the specific heat capacity of water and understand Carnot efficiency in thermal systems.

Thermodynamics

Q = mcΔT

Specific Heat

Heat = mass × c × temp change. J.

PV = nRT

Ideal Gas Law

P (Pa), V (m3), n (mol), T (K). Pa·m3.

ΔU = Q − W

First Law

Internal energy change. J.

ΔS = Q/T

Entropy

Change in disorder. J/K.

η = W/Q_H

Efficiency

Work out / heat in. Fraction.

P1V1 = P2V2

Boyle Law

At constant temperature. Dimensionless.

Modern Physics, Quantum Mechanics & Relativity Formulas

Explore fundamental modern physics principles using mass-energy equivalence ( $E = mc^2$ ), wave-particle duality, and de Broglie wavelength formulas. Easily solve quantum equations, photoelectric effect formulas, and radioactive decay equations (alpha, beta, and gamma decay). Use these essential physics formulas to calculate half-life equations, quantum numbers, and special relativity concepts for advanced problem-solving.

Modern Physics

E = mc²

Mass-Energy

Energy from mass. J.

E = hf

Photon Energy

h = 6.63×10&sup-34; J·s. J.

λ = h/mv

de Broglie

Matter wavelength. m.

KE = hf − φ

Photoelectric

Max kinetic energy of ejected electron. J.

N = N0 e&sup-λt

Radioactive Decay

Nuclei remaining at time t. Count.

t = t0/√(1−v²/c²)

Time Dilation

Relativistic time. s.

Frequently Asked Physics Formula Questions

Quick answers to common questions about essential physics formulas, units, and calculations.

What is the formula for force, mass, and acceleration?

The formula is F = ma (Force = mass × acceleration), derived from Newton's second law of motion. Force is measured in Newtons (N), mass in kilograms (kg), and acceleration in m/s².

How do you calculate kinetic energy using its formula?

Kinetic energy is calculated using KE = ½mv², where m is the mass in kg and v is velocity in m/s. Kinetic energy is always measured in Joules (J) and cannot be negative.

What is the wave speed equation and frequency relationship?

The wave speed equation is v = fλ (wave speed = frequency × wavelength). You can find frequency from wavelength by rearranging the equation to f = v / λ.

What is the specific heat capacity formula for water?

The specific heat capacity formula is Q = mcΔT. Water has a high specific heat capacity of approximately 4,200 J/kg·°C (or 4.184 J/g·°C).