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

Vocabulary

• Motion: An object’s change in position relative to a reference point.
• Frame of Reference: A system for specifying the precise location of objects in space and time.
• Displacement: The change in position of an object.
• Speed: The distance traveled divided by the time interval during which the motion occurred.
• Velocity: The speed of an object in a particular direction.
• Acceleration: The rate at which velocity changes over time; an object accelerates if its speed, direction, or both change.
• Force: An action exerted on a body in order to change the body’s state of rest or motion; force has magnitude and direction.
• Friction: A force that opposes motion between two surfaces that are in contact.
• Net Force: The combination of all forces acting

LASER = Light Amplification by Stimulated Emission of Radiation

A laser is actually an oscillator rather than a simple amplifier. The difference is that an oscillator has positive feedback in addition to the amplifier.

Light is understood in a general sense: electromagnetic radiation with a wavelength around 1 μm. Thus, one can have infrared, visible, or ultraviolet lasers.

The atomic medium with population inversion used in the laser is called the active medium. The positive optical feedback is obtained by placing the active medium between two mirrors. One of them (M1) totally reflects back the light (R1 = 1) to the active medium, while the other one (M2, called the output coupler) has a reflectivity less than unity (R2 < 1) and allows some... Continue reading "Introduction to LASER Technology: Types, Operation, and Applications" »

The 8 Thresholds of Increasing Complexity

• 1: The Big Bang: The origin of the universe.
• 2: The First Stars: Hydrogen fusion with helium; stars consist of hydrogen and helium, while dying stars create all other elements.
• 3: Creation of Heavy Chemical Elements: The synthesis of complex matter.
• 4: The First Planets: Chemical elements orbiting stars, bound together gravitationally and chemically.
• 5: Life: Complex molecules bound together chemically and physically, developing abilities for metabolism, homeostasis, reproduction, and adaptation.
• 6: Evolution of Homo Sapiens: Collective learning; language and teamwork drive progress.
• 7: Agriculture and the Birth of Civilization: Warmer climates led to the Neolithic Revolution, shifting from hunting and gathering

DEFINITIONS

DISTANCE

How much ground an object has covered/traveled.

DISPLACEMENT

The change in position of an object.

SCALAR QUANTITY

Quantity that only has magnitude and no direction.

VECTOR

Physical quantity that has both magnitude and direction.

CONSTANT SPEED

Speed that does not change.

VELOCITY

Speed in a given direction.

FRAME OF REFERENCE

A background used to judge motion/speed (precise location of an object).

INSTANTANEOUS SPEED

Speed at a given moment.

ENERGY

The capacity/power to do work/move an object by applying force.

MATTER

Anything that has mass and takes up space (how much matter).

WEIGHT

Measure of how gravity pulls matter.

SPEED

Amount of distance traveled in a certain amount of time.

AVERAGE SPEED

Total distance divided by total time.

TIME DISTANCE

Reading Section

1. C  11. B  21. C  31. A  41. D  51. A
2. B  12. C  22. D  32. C  42. ?
3. A  13. A  23. C  33. B  43. C
4. A  14. B  24. A  34. B  44. A
5. C  15. B  25. C  35. D  45. C
6. D  16. C  26. D  36. B  46. A
7. A  17. C  27. D  37. D  47. D
8. A  18. B  28. D  38. C  48. C
9. C  19. C  29. D  39. A  49. D
10. A 20. B  30. D  40. D  50. A

Writing and Language Section

1. D  11. B  21. C  31. C  41. C
2. C  12. A  22. B  32. A  42. ?
3. C  13. D  23. B  33. B  43. ?
4. B  14. A  24. D  34. D  44. ?
5. A  15. B  25. A  35. C
6. D  16. D  26. D  36. B
7. B  17. D  27. B  37. A
8. B  18. A  28. A  38. C
9. A  19. C  29. D  39. C
10. A 20. D  30. D  40. C

Math Sections

Math Section 3

1. C   11. B
2. D   12. A
3. B   13. A
4. D   14. C
5. A

Application of Atomic Structure to Static Electricity

• All material objects are composed of atoms.
• An atom consists of a nucleus and a vast region of space outside the nucleus.
• The nucleus of the atom contains positively charged protons and neutral neutrons.

Charging by Friction

The frictional charging process results in a transfer of electrons between the two objects which are rubbed together.

Triboelectric Series: materiales ordenados según la capacidad de tendencia de atraer electrones.

Electrizar: cargar una sustancia/cuerpo que era neutra.

Charging by Induction

Is a method used to charge an object without actually touching the object to any other charged object.

The Electroscope

An electroscope is a device which is capable of detecting the presence... Continue reading "Static Electricity and Fundamental Electric Principles" »

Understanding Waves and Energy Transfer

A wave is a disturbance that travels a distance, carrying the energy which generated it. When the wave travels through a medium, like water or air, it does not displace the particles of the medium.

Characteristics of a Wave

• Wavelength: This is defined as the distance between two adjacent peaks or troughs of the wave. It is expressed in metres (m).
• Frequency: This is the number of oscillations or complete movements that a wave produces in one second. Its unit in SI is the Hertz (Hz).
• Speed of Propagation: This is the distance, e, that the wave travels divided by the time taken, t. It is expressed in m/s.

  Waves travel at a constant speed. Therefore:

  V_wave = e/t

  Which implies:

  e = V_wave · t

• Amplitude: This is the

Engineering Safety Codes and Standards

Nowadays, the first concern of any engineer is safety. This concern has led to the introduction of worldwide codes and standards for the manufacture and maintenance of machines. Engineers began to understand the science behind the behavior of metals and other materials. The steam engine was one of the first machines which aroused interest in safety standards.

The steam engine works on a very simple scientific principle: when you heat water in a vessel, the molecules expand until, at a certain temperature, the liquid turns into a gas. The American Society of Mechanical Engineers (ASME) produced the Boiler Safety Code. Since then, the ASME has produced codes in all areas of mechanical engineering, including... Continue reading "Safety Codes and Friction in Mechanical Systems" »

Essential Wave Phenomena Definitions

Wave Terminology

• Node: A point of zero amplitude on a standing wave.
• Resonance: The increase in the amplitude of a vibration that occurs when external vibrations match an object's natural frequency.
• Antinode: A point of maximum amplitude on a standing wave.
• Standing Wave: A wave that appears to stand in one place, even though it is really two waves interfering as they pass through each other.
• Reflection: The bouncing back of an object or a wave when it hits a surface through which it cannot pass.
• Hertz (Hz): Unit of measurement for frequency.
• Frequency: The number of complete waves that pass a given point in a certain amount of time.
• Wavelength: The distance between two corresponding parts of a wave.
• Amplitude: The