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.

Home > Physics Notes > Mechanics

Mechanics — Classical Physics Study Notes & Formulas

Mechanics is the foundation of classical physics studying motion, forces, and energy. Explore kinematics SUVAT equations, Newton’s laws of motion, momentum, and work-energy formulas with clear notes and practice MCQs.

Classical Mechanics Study Notes

1. Kinematics — The SUVAT Equations

Kinematics describes how objects move without asking why. For any object with constant acceleration, five equations connect displacement (s), initial velocity (u), final velocity (v), acceleration (a), and time (t):

v = u + at
s = ut + ½at²
v² = u² + 2as
s = ½(u+v)t
s = vt − ½at²

On a velocity-time graph: slope = acceleration, area under line = displacement.

2. Newton Laws of Motion

First Law (Inertia): An object stays at rest or at constant velocity unless a net external force acts on it.

Second Law: F = ma. Net force equals mass times acceleration. Force and acceleration are in the same direction.

Third Law: Every force has an equal and opposite reaction acting on a different object. The rocket pushes gas backward; gas pushes rocket forward.

3. Work, Energy, and Power

Work W = Fs cosθ — work done = force × displacement × cos(angle). Kinetic energy KE = ½mv². Gravitational potential energy PE = mgh. Conservation of energy: in a closed frictionless system, KE + PE = constant. Power P = W/t.

4. Momentum, Impulse, and Collisions

Momentum p = mv (vector, SI unit kg·m/s). Impulse J = FΔt = Δp. In a closed system, total momentum is conserved. Elastic collisions conserve both momentum and KE. Inelastic collisions conserve momentum only.

Classical Mechanics Formula Sheet

Essential mechanics equations, force formulas, and SI units for quick revision.

Newton 2nd Law

F = ma

Net force = mass × acceleration

Unit: N (Newtons)

Kinetic Energy

KE = ½mv²

Energy of motion

Unit: J (Joules)

SUVAT (1)

v = u + at

Final velocity from initial + acceleration × time

Unit: m/s

Work Done

W = Fs cosθ

Work = force × displacement × cosθ

Unit: J (Joules)

Momentum

p = mv

Mass × velocity (vector)

Unit: kg·m/s

Weight

W = mg

Gravitational force on an object

Unit: N (Newtons)

Frequently Asked Questions About Mechanics

Quick answers to core classical mechanics questions and equation derivations.

What is classical mechanics?

Classical mechanics describes the motion of macroscopic objects under forces. It is built on Newton three laws and conservation laws for energy and momentum, and applies to everyday objects moving much slower than light.

What are the SUVAT equations used for?

SUVAT equations solve any constant-acceleration kinematics problem. Identify which three of the five variables (s, u, v, a, t) you know, pick the equation that uses those three plus your unknown, then solve.

What is the difference between elastic and inelastic collisions?

In elastic collisions, both momentum and kinetic energy are conserved (ideal billiard balls). In inelastic collisions, momentum is conserved but kinetic energy is lost to heat/sound/deformation (car crash).

What is the work-energy theorem?

The net work done on an object equals its change in kinetic energy: W_net = ΔKE = ½mv² − ½mu². This connects force, motion, and energy in a single equation.