Notes, summaries, assignments, exams, and problems for Physics

Fundamental Concepts in Physics

The Atom

An atom is composed of electrons, protons, and neutrons.

Temperature

Temperature is the physical quantity that describes the sensation of cold or hot, directly related to the average kinetic energy of molecules. It represents the average kinetic energy of each molecule.

Heat

Heat is the transfer of energy from one body to another due to a temperature difference. It is a form of energy that can be perceived through temperature variations.

Types of Thermal Expansion

• Linear Expansion
• Surface Expansion
• Volumetric Expansion

Thermodynamics

Thermodynamics is the branch of physics that studies heat transfer and the conversion of energy into its various forms.

Laws of Thermodynamics

• Zeroth Law
• First Law
• Second Law

Zeroth Law

Analyzing Through the Looking-Glass as Children's Literature

Through the Looking-Glass is a straightforward fantasy novel written by Lewis Carroll. As a work of fantasy fiction, it is widely categorized as children's literature.

The Role of Fantasy in Children's Literature

Children's literature is often rooted in fiction, detached from the constraints of the real world. To be effective, it must balance descriptive depth with a strong sense of fantasy. Key elements include:

• Peculiar Creatures: The inclusion of weird and wonderful beings.
• Anthropomorphism: Children interacting with toys and animals as if they were animate.
• Imagination: The power of dreaming to provide happiness and escapism.

Carroll's Mastery of the Genre

Carroll successfully incorporates... Continue reading "Through the Looking-Glass: A Masterpiece of Children's Fantasy" »

Electrostatics Fundamentals

This document covers key concepts in electrostatics, including properties of electric charge, Coulomb's Law, and electric fields.

Properties of Electric Charge

Here are four fundamental properties of electric charge:

1. Additivity of Charges: The total charge of a system is the algebraic sum of all individual charges present in the system.
2. Conservation of Charge: The total charge of an isolated system remains unchanged over time. Charge can neither be created nor destroyed, only transferred.
3. Quantization of Charge: The total charge of a body is always an integral multiple of a basic quantum of charge, denoted as 'e'. This means charge q can only exist as q = ±ne, where n is an integer (1, 2, 3, ...).
4. Interaction of Charges:

Shear Stress in Beams

• 16.1 Rectangular beam: b = 100 mm, d = 250 mm, L = 3 m, w = 40 kN/m → Find τmax + distribution
• 16.2 Triangular section: b = 100 mm, h = 150 mm, F = 13.5 kN → Find τmax + distribution
• 16.3 Circular section: d = 100 mm, F = 30 kN → Find τmax + distribution
• 16.4 I-section: Flange = 150×20 mm, Web = 300×10 mm, F = 50 kN → Find τmax
• 16.5 I-section: D = 350 mm, B = 200 mm, web = 12.5 mm, flange = 25 mm, F = 200 kN → Shear stress distribution
• 16.6 T-section: F = 100 kN, I = 113.4 × 10⁶ mm⁴ → Shear at points + distribution
• 16.7 Unequal I-section: σc = 17.5 MPa, F = 100 kN → Bending moment + shear distribution
• 16.8 Irregular section: F = 20 kN → Shear at points + distribution
• 16.9 Square (diagonal): Diagonal

1. 💌 ਨਿੱਜੀ ਚਿੱਠੀ (Personal Letter)

ਉਦੇਸ਼: ਛੋਟੇ ਭਰਾ ਨੂੰ ਸਖ਼ਤ ਮਿਹਨਤ ਕਰਨ ਦੀ ਸਲਾਹ ਦੇਣ ਲਈ।

ਮਕਾਨ ਨੰ: 304, ਸੈਕਟਰ-14, ਪਟਿਆਲਾ।
ਮਿਤੀ: 8 ਦਸੰਬਰ, 2025

ਪਿਆਰੇ ਛੋਟੇ ਵੀਰ ਅਮਨ,
ਮੈਂ ਇੱਥੇ ਠੀਕ-ਠਾਕ ਹਾਂ ਅਤੇ ਉਮੀਦ ਕਰਦਾ ਹਾਂ ਕਿ ਤੁਸੀਂ ਵੀ ਠੀਕ ਹੋਵੋਗੇ। ਮੈਨੂੰ ਪਿਤਾ ਜੀ ਦਾ ਪੱਤਰ ਮਿਲਿਆ ਜਿਸ ਵਿੱਚ ਉਨ੍ਹਾਂ ਨੇ ਦੱਸਿਆ ਕਿ ਤੁਹਾਡਾ ਧਿਆਨ ਪੜ੍ਹਾਈ ਤੋਂ ਹਟ ਰਿਹਾ ਹੈ ਅਤੇ ਤੁਹਾਡੇ... Continue reading "ਪੰਜਾਬੀ ਵਿੱਚ ਪੱਤਰ ਲਿਖਣ ਦੇ ਨਮੂਨੇ: ਨਿੱਜੀ, ਸਰਕਾਰੀ ਅਤੇ ਵਪਾਰਕ" »

Biology Fundamentals

Genetics: DNA and RNA

• DNA: Double helix structure; carries genetic information. Bases pair A–T and C–G.
• RNA: Single strand; uses Uracil (U) instead of Thymine (T); assists in protein synthesis.

Cell Division

• Mitosis: Results in two identical daughter cells; essential for growth and repair.
• Meiosis: Results in four genetically different cells; produces gametes (sperm and egg).

Chromosomes

• Humans possess 23 pairs, totaling 46 chromosomes:
  • 22 pairs are autosomes.
  • 1 pair consists of sex chromosomes (X/Y).
• Sex determination: Males are XY; Females are XX.

Inheritance Principles

• Dominant Allele: Expressed even if only one copy is present.
• Recessive Allele: Expressed only when two copies are present.
• Use Punnett squares to predict trait outcomes

Thermodynamics

First Law of Thermodynamics (Law of Energy Conservation)

Energy cannot be created or destroyed; it can only change forms.

Formula: ΔU=Q−W

Where: ΔU is the change in internal energy of the system, Q is the heat added to the system, W is the work done by the system.

Explanation: The total energy in a closed system remains constant. Energy can be transformed from one form to another (e.g., heat energy to mechanical energy).

Second Law of Thermodynamics

Key Concept: The total entropy (disorder) of an isolated system always increases or remains constant.

Formulas:

Entropy Change for Reversible Process: ΔS=Qrev /T

Where: ΔS is the change in entropy. Qrev is the heat added in a reversible process. T is the absolute temperature. Qirr is... Continue reading "Thermodynamics and Simple Harmonic Motion" »

SRML Half-Yearly Examination - 2080

Class: 9 | Subject: Science and Technology | Full Marks: 50 | Time: 2 Hours

Answer all questions.

Group - A: Multiple Choice Questions (8x1 = 8)

• a. What is the multiplier of the prefix 'micro'? (a) 10⁻⁶ (b) 10⁻⁹ (c) 10⁶ (d) 10⁻³
• b. What is the stalk of a mushroom called? (a) Pileus (b) Gills (c) Stipe (d) Hyphae
• c. Who was the proponent of the theory of natural selection? (a) Hugo de Vries (b) Charles Darwin (c) Lamarck (d) Gregor Johann Mendel
• d. If a load of 400 N is moved using an effort of 50 N, what is the Mechanical Advantage (MA)? (a) 8 (b) 50 (c) 400 (d) 100
• e. Which is not a source of non-renewable energy? (a) Coal (b) Biogas (c) Kerosene (d) Petrol
• f. Which is an example of a longitudinal wave?

Chapter 27: Bridge Engineering Through History

Truss beams are strengthened by a stiff framework above or beneath the arch, supported by arch suspension, hanging cables, or pontoons made of boats or devices. Cantilever beams are supported only on one end.

Roman and Medieval Bridges

The largest Roman bridges were aqueducts. The best-known example is the Pont du Gard in France. During the Middle Ages, bridges were placed under the care of a religious order. These bridges were strongly fortified with huge towers. The most famous bridge of this period was the London Bridge, located over the Thames River. It eventually fell into disrepair and required reconstruction.

Renaissance and Modern Bridges

Three notable bridges built during the Renaissance include:... Continue reading "Evolution of Bridge Engineering and Skyscraper Architecture" »

Bernoulli's Equation and Energy Balance

Since the fluid is incompressible, A₁Δx₁ = A₂Δx₂ = ΔV.

Work–Energy Principle Derivation

The work done on the fluid is due to the pressure acting on it.

Therefore, the work done, ΔW = F₁Δx₁ - F₂Δx₂

= P₁A₁Δx₁ - P₂A₂Δx₂

= P₁ΔV - P₂ΔV

ΔW = (P₁ - P₂) ΔV

Change in kinetic energy, ΔKE = KE₂ - KE₁

= &frac12 mv₂² - &frac12 mv₁²

ΔKE = &frac12 m (v₂² - v₁²)

= &frac12 ρ ΔV (v₂² - v₁²)

Change in potential energy, ΔPE = PE₂ - PE₁

= m g h₂ - m g h₁ = m g (h₂ - h₁)

Since m = ρ ΔV, ΔPE = ρ ΔV g (h₂ - h₁)

Using the work–energy principle,

ΔW = ΔKE + ΔPE

(P₁ - P₂) ΔV = &frac12 ρ ΔV (v₂² - v₁²) + ρ ΔV g (h₂ - h₁)

Therefore, P₁ - P₂ = &frac12 ρ (v₂² - v₁²) + ρ g (h₂ - h₁)

Rearranging