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

The Importance of Light

Light is an essential form of energy for life on Earth. It is electromagnetic radiation within a specific portion of the electromagnetic spectrum. The term usually refers to visible light, which is detectable by the human eye and is responsible for our sense of sight.

How Light Travels

Light travels as transverse waves, similar to ripples in a tank of water. The direction of vibration in these waves is at 90° to the direction of travel. Because light travels in straight lines, you should always use a ruler when representing a ray of light in a drawing.

Unlike sound waves, light can travel through a vacuum (empty space). It does not require a medium to propagate, though it can pass through:

• Transparent substances: Matter

Fundamental Concepts in Earth Physics

Elastic Moduli and Seismic Waves

Elastic Moduli Definitions

• Young's Modulus (Y): Describes the fractional change in length of an object when subjected to a tensile stress. The formula is: Y = (F/A) / (ΔL/L₀)
• Bulk Modulus (K): Describes how a fractional change in volume depends on the applied pressure.
• Shear Modulus (G): Describes how an angle of shear depends upon a tangential stress.

Seismic Wave Types

• P-wave (Primary Wave): Characterized by compressional and expansion motion.
• S-wave (Secondary Wave): Characterized by shear motion.

Demonstration of Radiometric Age Dating

Derivation of the Decay Equation

If the decay rate is equal to $\lambda$, the probability that a given nucleus will decay in a time interval... Continue reading "Geophysical Principles: Elasticity, Magnetism, and Radiometric Dating Formulas" »

Lens

What is a real image?

An image where real rays intersect

What is a virtual image?

An image that appears to be coming from behind the mirror

Describe the law of reflection as a relationship between the angle of incidence, the angle of reflection, and the normal.

The angle of incidence, angle of reflection and normal all lie in the same plane

Describe the kinds of images that can be formed by plane mirrors.

Only virtual images, little distortion

What type of mirror produces only diverging rays?

Convex

What type of mirror can produce both converging and diverging rays?

Concave

Describe what kind of mirror you would use if you needed to view a large, spread-out area in a small mirror.

Convex

Compare the shapes of convex and concave mirrors. How are they

Key Benefits of Using Solar Power

• Clean energy
• Renewable energy

Future of Photovoltaic Systems in Industrial and Developing Countries

Does the future hold a place for photovoltaic (PV) systems in both industrial and less developed countries?

Yes, because the problem of CO2 emissions is getting bigger, and it is necessary to invest immediately in new sources of renewable energy.

Advantages of Off-Grid PV Systems for Emergency Applications

What are some advantages of using off-grid PV systems for emergency call boxes and emergency warning signals?

• They save the cost of extending power lines to far-away locations.
• In the event of an electrical failure, they will still function.

Major Disadvantage of PV Systems

PVs require light to operate. What is one big

True/False

t: A strong acid is one that will completely ionize

f: When blue litmus paper is placed in a weak acid, it will turn a darker shade of blue

f: When pH paper provides a reading which says it has a pH of 9, the substance is considered a weak acid.

f: Alpha, Beta, and Gamma are all forms of nuclear radiation that contain either positive or negative charges.

t: Fission is the process where a large nucleus splits unto two smaller nuclei.

f: The most common isotope of carbon that is used for radioactive dating is carbon-13.

t: Static friction is friction that occurs when an object is not moving.

f: When an object is accelerating but it is not traveling in a straight line, it must be moving vertically.

t: Friction is force that always opposes the... Continue reading "Science True/False and Multiple Choice Questions" »

The Scientific Method and Celestial Motion

In the Scientific Method, a hypothesis must be both testable and falsifiable. When observing the heavens, sidereal measurements are relative to the stars, while synodic measurements are relative to the Sun; for instance, the Moon is full every synodic month.

Kepler's Laws of Planetary Motion

• Kepler's 1st Law: Orbits are ellipses with two foci; the Sun is at one focus. A higher eccentricity (e) indicates a more elliptical orbit.
• Kepler's 2nd Law: The Law of Equal Areas.
• Kepler's 3rd Law: P² = a³, where P is the period in years and a is the semi-major axis in AU.

The Solar System Rotation Curve is defined by the formula v = sqrt(GM/r), where v is orbital velocity and r is the distance from the Sun.

Newtonian

Thermal Energy

Thermal energy is the average kinetic energy of the atoms or molecules in a substance.

Thermal Energy and Changes of State

When a change of state occurs, the energy transferred in heating up the substance is used to break the bonds between the molecules. The energy transferred does not increase the thermal energy but rather increases the internal energy of the substance.

Key Concepts

• The particles of a substance are in constant motion, and this increases as the substance heats up.
• Thermal energy is the average kinetic energy of the particles of a substance.
• During a change of state, the energy transferred in the heating process is used to break the bonds between molecules without increasing its thermal energy.

Temperature: Measurement

Angular Kinetics

Center of Mass

Point around which mass or weight is considered to be concentrated.

Determining COG

• Balance method
• Suspension method
• MRI reconstruction
• Segmental

Segmental Limitation

• Based on Caucasian male cadavers
• Completed in 1930s
• Based on segments being truncated cones

Mechanical Stability

Ability to maintain vertical projection of CG within base of support.

Ways to Increase MS

• Increase mass
• Increase friction between body and surface
• Increased size of base support

Angular Inertia

Property of an object to resist changes in its angular motion.

Factors Influence

Radius has larger influence than mass.

Center of Mass

Point where gravitational force is applied balance

Radius of Gyration

Point where mass can conceptually be concentrated such that it does... Continue reading "Angular Kinetics and Biomechanics" »

It is the view that our mind and our brain are different things. One way to understand this concept is to consider our self as a container including our physical body and physical brain along with a separate non-physical mind, spirit, or soul. The mind, spirit, or soul is considered the conscious part that manifests itself through the brain in a similar way that picture waves and sound waves manifest themselves through a television set. The picture and sound waves are also non-material just like the mind, spirit, or soul.

Elements of Design

1. Lines

• Vertical lines: Create height and grandeur.
• Horizontal lines: Establish relationships and calm the mood.
• Diagonal lines: Generate movement and direction.
• Curved lines: Convey familiarity, comfort, and relaxation.
• Thick lines: Direct the eye without distraction.

2. Shapes

3. Color

4. Value

5. Texture

6. Space and Perspective

Principles of Design

1. Space

2. Alignment

3. Repetition

4. Contrast

5. Pattern

6. Rhythm and Movement

7. Proportion

8. Balance

9. Unity

10. Emphasis

Principles of Design

1. Similarity

2. Continuation

3. Closure

4. Proximity

5. Figure

6. Symmetry