Essential Vocabulary: Definitions and Terms
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- Abacus: A wooden box with ten parallel wires and ten beads on each wire, used to learn to count.
- Abbot (Abbess f.): The superior of a monastery or abbey.
- Abdicate: To renounce power (e.g., the king abdicated).
- Abolish: To remove a law (e.g., the law was abolished).
- Aboriginal: A primitive inhabitant of a country. / Native: A plant or animal from its original place of residence.
- Absolve: To leave a defendant guilt-free (e.g., the prisoner was acquitted).
- Greedy: Wanting something with great force; thirsty
Fundamental Laws of Physics: Motion, Energy, and Electricity
Newton’s Laws of Motion
Newton’s First Law of Motion
An object continues to remain at rest or in a state of uniform motion along a straight line unless an external unbalanced force acts on it.
Newton’s Second Law of Motion
The rate of change of momentum is proportional to the applied force, and the change of momentum occurs in the direction of the force.
Newton’s Third Law of Motion
Every action force has an equal and opposite reaction force which acts simultaneously.
Work
Work done by a force acting on
Read MoreFluid Dynamics: Key Concepts and Principles
Fluid Energy
- Kinetic Energy
- Potential Energy
- Internal Energy
Kinematic Viscosity
Dynamic Viscosity/Density
Streamlines
Tangent to flow velocity. Velocity potential is zero when the flow is irrotational or vorticity is “0”.
Bernoulli’s Equation is Applicable When
- Along a Streamline
- Inviscid
- Steady
- Incompressible
- No work is done
- No heat transfer
Bernoulli Equation was Developed by
Daniel Bernoulli and Leonhard Euler
Apply Shear Stress
- Solids: Will stop deforming
- Fluids: Continuously deform
Gage Pressure
Positive Pressure
Read MoreFluid Dynamics: Reynolds Number, Manometers, and Bernoulli’s Theorem
Reynolds’ Experiment
Osborne Reynolds, an Irish engineer, conducted a series of experiments in the 1880s to investigate the nature of fluid flow. His most famous experiment involved flowing water through a pipe and observing the flow behavior.
Procedure
Reynolds varied the flow rate of water through the pipe and observed the flow behavior using a dye. He noted that at low flow rates, the dye flowed smoothly and steadily through the pipe, indicating laminar flow. As the flow rate increased, the dye
Read MoreLasers and Optical Fibers: Principles and Applications
Lasers
Q1. Distinguish between spontaneous and stimulated emission of radiations (3 points). (3 Marks)
| Aspect | Spontaneous Emission | Stimulated Emission |
|---|---|---|
| Definition | Radiation emitted by an atom or molecule as it transitions from a higher energy state to a lower one, without external influence. | Radiation emitted when an external photon of appropriate energy interacts with an excited atom, causing it to release a photon identical to the incoming one. |
| Directionality | Emission is random and occurs in all directions, |
Galactic Structures and Universe Expansion: Key Insights
Structure of the Milky Way
Major Components
- Thin Disk: Contains most of the galaxy’s gas, dust, young stars, and active star formation (e.g., massive young stars in spiral arms).
- Thick Disk: Older stars, less gas and dust.
- Bulge: Dense cluster of old stars; includes the galactic center and possibly a bar structure.
- Halo: Sparse outer region containing ancient Population II stars and globular clusters; dominated by dark matter.
Challenges in Mapping
- The Sun’s position inside the galaxy obscures our view.