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

Gauss's Law in Electromagnetism

For a closed surface represented by i, the number of electric field lines leaving the surface is equal to the number of lines entering it. This is consistent with the fact that no net charge is enclosed by the surface. However, for the closed surface ii in the same figure, there is a net outward flux, indicating a net positive charge enclosed.

The situation is radically different for magnetic fields, which are continuous and form closed loops. Examine the Gaussian surfaces represented by i or ii. Both cases visually demonstrate that the number of magnetic field lines leaving the surface is balanced by the number of lines entering it. The net magnetic flux is zero for both surfaces. This is true for any closed surface.... Continue reading "Electromagnetic Principles: Flux, Induction, and AC Power Generation" »

EQUATIONS

EMF and Potential Difference

Resistance

CURRENT

POTENTIAL DIFFERENCE (P.D.)

RESISTANCE

OHMIC CONDUCTORS

Understanding Motion and Forces

Acceleration Defined

Acceleration occurs when unbalanced forces cause a change in motion. It is directly related to the size and direction of the applied force. An object accelerates in the same direction it is pushed or pulled. Greater force results in greater acceleration.

Acceleration is inversely related to an object's mass; a large mass results in small acceleration for a given force.

Newton's Second Law of Motion

Newton's Second Law states that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass.

Understanding Weight and Units

Weight is a force, calculated as mass multiplied by the acceleration due to gravity (w = m ⋅ g).

Key Physics Units

• Force

Understanding Pendulums

State the following terms:

• Pendulum
• Simple pendulum
• Conical pendulum

Ans: A tiny mass (assumed to be a point object and called a bob) connected to a long, flexible, massless, inextensible string, and suspended to a rigid support is called a pendulum.

If a tiny mass (assumed to be a point object and called a bob) connected to a long, flexible, massless, inextensible string, and suspended to a rigid support is made to oscillate in a single vertical plane, it is said to be a simple pendulum.

A tiny mass (assumed to be a point object and called a bob) connected to a long, flexible, massless, inextensible string, and suspended to a rigid support revolves in such a way that the string moves along the surface of a right circular cone... Continue reading "Understanding Pendulums, Fluid Pressure, and Molecular Forces" »

Middle English Pronouns, Verbs, and Lexical Change

2nd Person Forms and Address

2nd p. sg and pl in the Middle English period: Very different depending on whom you were addressing. The upper class used “ye” (plural of politeness), and lower-class speakers also used “ye” to address the upper class. The lower class among themselves used “thou” (singular). The upper class also used it to address the lower class. Objects: “thee” (sg), “you” (pl).

Pronouns and Relative Forms

• Relative pronouns and demonstratives: OE pe / demonstrative + pe.
• 12th century: that appears as a relative/interrogative marker.
• Introduction of wh-relatives and interrogative forms — frequency increases into Modern English.
• One replaces the OE indefinite pronoun

Fundamental Concepts of Energy and Work

• 1. Which of these is measured in joules? Energy
• 2. The two main types of energy discussed: Kinetic & Potential
• 3. The work-energy theorem: The net work done on an object equals the change in its kinetic energy.
• 4. Kinetic energy: The energy of movement.
• 5. The Law of Conservation of Energy: Energy can neither be created nor destroyed.
• 6. Potential energy: The energy of position.
• 7. Pendulum potential energy: Highest when at the top of its swing.
• 8. Inelastic collision: A collision where some energy is converted into other forms.
• 9. Chemical energy: Energy stored in chemical bonds.

Machines, Power, and Efficiency

• 6. Which machine has 100% efficiency? No real machine has 100% efficiency.
• 7. Rube Goldberg: Famous

Measurement of Pressure Losses in Pipes

1. Measurement of pressure losses in pipes under pressure can be made with: Piezometers

Flow Number and Linear Losses Factor

2. The flow number a is expressed in units: This value is dimensionless.

3. The linear losses factor f can be determined on the basis of: Relative roughness and Reynolds Number.

Orifice and Pump Head

4. The ISA orifice can be used to measure: Flow rate.

5. The pump head can be determined from: Bernoulli equation.

Absolute Roughness and Outlet Pressure

7. Absolute roughness can be determined: From Colebrook-White's formula.

8. The outlet pressure in the nozzle depends on: Flow rate in the nozzle.

Hydrostatic Pressure and Force

9. The unit of hydrostatic pressure in the SI system: kg/(m*s^2)

10.

Q4) The most widely used equation for estimating visibility is the Koschmeider equation:

                              Lv = 1200 km x µg/m³ / particle concentration

Where Lv is the visual range, the distance at which an average person can barely distinguish a dark object (such as a mountain or skyscraper) against the sky. This equation is an approximation, based on an average set of atmospheric particles.

• In the Grand Canyon and the surrounding area, on clear days, one can easily see mountains 120 miles away. What is the probable concentration of particles in the atmosphere when one can see that far?
• If the particle concentration in the atmosphere is increased by 1.5 µg/m³, what is the percentage decrease in the visual

Verb Alternations in English

The body-part possessor ascension alternation is characterized by a change in the expression of a possessed body part. The possessed body part may be expressed as the direct object of the verb (e.g., Margaret cut Bill’s arm), or the possessor may be expressed as the object of the verb with the possessed body part expressed in a prepositional phrase (e.g., Margaret cut Bill on the arm).

Examples:

• NPagent Verb [NP’s body-part]theme: Margaret cut [Bill’s arm].
• B-p possessor ascension construction: NPagent Verb [NPtheme] [on the body-part]: Margaret cut [Bill] [on the arm].

The body-part possessor ascension requires a sub-event ACT that involves contact. Consequently, "break" verbs typically do not participate in this... Continue reading "Verb Alternations: Body-Part, Causative, and Dative Shifts" »