Study Document

By Niraj Kumar (Founder & Educator, BR DOT HUB) • Category: EXAM NOTES • Reading Time: 8 Mins • Updated: September 2026

Date Start: 01 Oct 2026, 08:00 AM

Published: true

General Science: Physics Revision Sheet

Newton's First Law (Inertia): An object continues in state of rest or uniform motion unless acted upon by external force.

Newton's Second Law: $\mathbf{F} = m\mathbf{a} = \frac{d\mathbf{p}}{dt}$

Newton's Third Law: Action and reaction are equal in magnitude and opposite in direction.

Work, Energy & Power:

$\text{Work} = \mathbf{F} \cdot \mathbf{d} = F d \cos\theta$ (Unit: Joule)

$\text{Kinetic Energy} = \frac{1}{2}mv^2$

$\text{Potential Energy} = mgh$

$\text{Power} = \frac{\text{Work}}{\text{Time}}$ (Unit: Watt; $1\text{ HP} = 746\text{ W}$)

Speed of Light: $c = 3 \times 10^8\text{ m/s}$ in vacuum.

Refractive Index: $\mu = \frac{c}{v} = \frac{\sin i}{\sin r}$ (Snell's Law)

Total Internal Reflection (TIR):

Conditions: Light travels from denser to rarer medium; Angle of incidence > Critical angle.

Applications: Optical fiber cables, Mirage formation, Sparkling of diamonds.

Lens Formula: $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$

Mirror Formula: $\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$

Power of Lens: $P = \frac{1}{f\text{ (in meters)}}$ (Unit: Diopter, D)

Temperature Scales: $\frac{C}{5} = \frac{F - 32}{9} = \frac{K - 273.15}{5}$

Anomalous Expansion of Water: Maximum density occurs at $4^\circ\text{C}$ ($1000\text{ kg/m}^3$).

Heat Transfer Modes: Conduction (solids), Convection (fluids), Radiation (no medium needed, e.g., Sun to Earth).