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

Simple Machines and Mechanical Advantage

Simple machines are devices that make work easier. They do this by changing the magnitude or direction of a force. Many simple machines are combined to create complex machines.

Wheel and Axle

A wheel is attached to a central axle so that when one turns, the other must turn. A longer motion at the wheel's edge is converted to a shorter, more powerful motion at the axle. Conversely, a short, powerful force at the axle moves the wheel's edge a greater distance.

Pulley System

A single pulley simply reverses the direction of a force. When two or more pulleys are connected together, they permit a heavy load to be lifted with less force. The trade-off is that the rope's end must move a greater distance than the... Continue reading "Simple Machines: A Comprehensive Guide to Mechanical Advantage" »

- Scalars and Vectors

• Scalars require magnitude and unit (distance, time, speed, mass)

• Vectors require magnitude, unit, AND direction (displacement, velocity, acceleration, force)

• Force vectors are drawn with their tails attached to the point of application on the object.

• 1D vectors use right/left, up/down, +/-

• 2D vectors described using angles, measured clockwise and anticlockwise from the vertical and horizontal

- Adding Vectors

• 1D vector: make one direction (up, right) a positive value and the opposite direction (down, left) a negative value, then add them all up.

• 2D vector: draw the first vector in the appropriate direction, then the second vector from the head of the first. Then use a² + b² = c² to find the hypotenuse... Continue reading "Introduction to Motion, Forces, and Momentum in Physics" »

State the properties of solid state.

^{Ans: Solid has a definite shape, mass, and volume. The matter in its solid-state has the lowest amount of thermal energy as there is no space for the particles to move around. Solid tends to have a great electrical conductivity.}

What is a mixture? Give examples.

^{Ans: A mixture is a substance made by combining two or more different materials in such a way that no chemical reaction occurs. A mixture can usually be separated back into its original components. Some examples of mixtures are a tossed salad, salt water and a mixed bag of M&M's candy.}

What is solubility?

^{Ans: Solubility: The maximum amount of solute that can dissolve in a given amount of solvent. The maximum amount of a substance that can be dissolved}

Radiation occurs when energy is transferred by waves from a source to the food. The waves themselves are not actually heat energy but are changed into heat energy when they strike the food being cooked. (Light waves, radio waves, and X-rays are examples of radiation not used for cooking.)

Two kinds of radiation:

Infrared: In a broiler, an electric element or a ceramic element heated by a gas flame becomes so hot it gives off infrared radiation, which cooks the food. High-intensity infrared ovens are designed to heat food rapidly.

Microwave: radiation generated by the oven penetrates partway into the food, where it agitates the molecules of water. The friction this agitation causes creates heat, which cooks the food. Because microwave radiation

JANUARY

Adrian is 13 years old. I prepare his resolutions for the new year. He has a point on his chin. He feels bad because his parents separated. His dog is sick because he ate a model of a boat from Adrian's father. Lucas, the neighbor, visits Adrian's mother every day. Adrian meets Pandora and falls in love, but she ends up with Adrian's best friend, Nigel. At school, Adrian has a support group for the elderly where he helps Bert Baxter. Lucas and his wife divorce, and Adrian's father is jealous of him.

FEBRUARY

Adrian's parents no longer have housework. She just spends the day with Lucas looking at porn magazines. Adrian has his first porn dream. Lucas stays with Adrian's family because his wife took all the furniture. He only has a Valentine'... Continue reading "Adrian's Coming of Age Story: A Year of Challenges and Love" »

Adjectives

The simplest definition of an adjective is that it is a word that describes or clarifies a noun. Adjectives describe nouns by giving some information about an object’s size, shape, age, color, origin, or material.

It’s a big table. (size)

It’s a round table. (shape)

It’s an old table. (age)

Possessive adjectives - my, your, his, her, its, our, your, their -

Modify the noun following it to show possession.

Examples:

I'll get my bag.

Is this your luggage?

Comparative adjectives

Used to compare differences between two objects they modify (larger, smaller, faster, higher).

My house is larger than hers.

This box is smaller than the one I lost.

Your dog runs faster than Jim's dog.

Superlative adjectives

Used to describe an object at the upper... Continue reading "Understanding Adjectives and Adverbs: Definitions and Examples" »

What are New Year's resolutions?

New Year's resolutions are a person's (good) intentions for the coming year.

Why does Adrian think that his spot is growing?

Adrian thinks that his spot is growing because his mother doesn't know about vitamins.

When the dog has the operation, what does the vet find? Why?

The vet finds many things in the dog's stomach. There were even plastic pirates from Adrian's father's model ship. The dog had eaten these things.

Exactly how old is Adrian at the beginning of his diary?

Adrian is 133/4 years old at the beginning of his diary.

Why did Adrian think Nigel was being polite when he told him that he was going to the doctor?

Adrian thought that Nigel was being polite because Nigel said he couldn't see Adrian's spot.

Why did

Evolution of Animals

Past Forms and Modern Counterparts

1. Changes in Animal Views

Our view of modern animals has changed due to the evolutionary adaptations within their species, as revealed by scientific studies.

2. T-Rex of the Ocean

Ancestors of the blue whale were nicknamed the "T-Rex of the ocean" because they possessed razor-sharp teeth.

True or False Statements

Justify your answers with evidence from the provided text.

3. Existence of Animals 50 Million Years Ago

True. Fifty million years ago, familiar animals existed, but in almost unrecognizable forms.

4. Resemblance of Large Dogs to Modern Whales

True. Whales, which now live in the water, once had legs and lived on land, possibly resembling large dogs.

5. Immediate Loss of Whale Hind Legs

False.

1) A wave has the form

When x = 0, the wavelength is

By applying continuity conditions at x = 0, find the amplitude A_x>0 (in terms of A) and phase Φ of the wave in the region x > 0. Use any variable or symbol stated above as necessary.

2) An electron is trapped in an infinite well of width L = 1.87nm. What are the three longest wavelengths permitted for the electron's de Broglie waves?

The wave function must be zero everywhere the potential is infinite. So the wave function is zero outside the well. Since the wave function must be continuous, the wave function inside the well must go to zero at the edges of the well. Thus, only certain discrete wavelengths are allowed.

3) A particle is described by the wave function ψ(x) = b(a² - x²) for

Matthew Arnold's Touchstone Method of Criticism was really a comparative system of criticism.  Arnold was mostly a classicist.  He admired the ancient Greek, Roman and French authors as the models to be followed by the modern English authors.  The old English like Shakespeare, Spenser or Milton were also to be taken as models.  Arnold took selected passages from the modern authors and compared them with selected passages from the ancient authors and thus decided their merits.  This method was called Arnold's Touchstone Method.             However, this system of judgement has its own limitations.  The method of comparing passage with a passage is not a sufficient test for determining the value of a work as a whole.  Arnold... Continue reading "dsf" »