## Crystals in metals

States of matter: Why do metals have the properties that they have?

(Section under construction)

Solid / Liquid / Gas

Metal is a type of solid

Metal is usually an imperfect crystal

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At any temperature above absolute zero, atoms vibrate, so even in solids the atoms are always somewhat in motion

Iron atoms, like many other metals, take on this shape

Body-Centered Cubic (BCC) Structure: there are 8 atoms at the 8 corners, and one atom in the centre of the unit cell. This structure is then repeated over and over.

“The structure of iron atoms isn’t continuous throughout the entire paper clip. When a metal cools and is transitioning from liquid to solid, its atoms come together to form tiny grains, or crystals. Even though the crystalline structure does not continue from crystal to crystal, the crystals are bound to one another. In this diagram, each square represents an individual atom.”

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atoms held together with metallic bonds

(add pics here)

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Defects break the bonds

“When a metal crystal forms, the atoms try to assemble themselves into a regular pattern. But sometimes there isn’t an atom available to fill in a space, and sometimes a growing layer is halted by other growing layers. There are many imperfections within each crystal, and these flaws produce weak points in the bonds between atoms. It is at these points, called slip planes, that layers of atoms are prone to move relative to adjacent layers if an outside force is applied. Adding other elements to a metal can counteract the effects of the imperfections and make the metal harder and stronger. Carbon, for example, is added to iron to make steel, and tin is added to copper to make bronze.”

Atoms can slip into a new position

Slipping

Metal atoms can bend

Heat can loosen the fixed positions of metal atoms

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PBS NOVA: Building on Ground Zero – The Structure of Metals

PBS NOVA: Interactive Structure of Metals

PBS NOVA: Engineering Ground Zero

## Learning Standards

Massachusetts Science and Technology/Engineering Curriculum Framework

High School Chemistry

HS-PS2-6. Communicate scientific and technical information about the molecular-level structures of polymers, ionic compounds, acids and bases, and metals to justify why these are useful in the functioning of designed materials.*

PS1.A Structure of matter. That matter is composed of atoms and molecules can be used to explain the properties of substances, diversity of materials, how mixtures will interact,

states of matter, phase changes, and conservation of matter. States of matter can be modeled in terms of spatial arrangement, movement, and strength of interactions between particles.

PS2.B Types of interactions. Electrical forces between electrons and the nucleus of

atoms explain chemical patterns. Intermolecular forces determine atomic composition, molecular geometry and polarity, and, therefore, structure and properties of substances.

## MCAS Open Response questions

**Content Objectives**: SWBAT construct answers to open-response questions on the physics MCAS.

2015, High School Intro Physics: sample open response question

2011 sample open response questions

2012 sample open response questions

2013 sample open response questions

2014 sample open response questions

2015 sample open response questions

2016 sample open response questions

**Learning Standards**:- For answering open-response questions – ELA Core Curriculum
- CCRA.R.1 – Read closely to determine what the text says explicitly and to make logical inferences from it; cite
- specific textual evidence when writing or speaking to support conclusions drawn from the text.
- For answering problems involving equations: Massachusetts Curriculum Framework for Mathematics
- Functions: Connections to Expressions, Equations, Modeling, and Coordinates.
- Determining an output value for a particular input involves evaluating an expression; finding inputs that yield a
- given output involves solving an equation.

## Fuses

Fuses

### You can use adapters to turn one outlet into two… two outlets into four, and so on. What happens if you turn on all the devices connected to all these cords at once? They draw a lot of current through the wires to that outlet – and those wires can overheat, and start an electrical fire.

### Electrical fire

### This is why we need something in the house which can detect abnormally high electrical currents – and cut them off.

### Circuit breakers and fuse boxes.

### Here we see what could be a potentially fatal accident – a wet electrical appliance could conduct enough electricity to kill a person. How can we avoid this?

### “A ground fault circuit interrupter (GFCI) or Residual Current Device (RCD) is a device that shuts off an electric power circuit when it detects that current is flowing along an unintended path, such as through water or a person.”- Simple Wikipedia

### A GFCI on a hair dryer.

Lab Measuring Voltage Current DC circuits

- Learn how to build a simple circuit, measure voltage, and current
- Build a DC series circuit and DC parallel circuit

==========================

## The fuse

The fuse breaks the circuit if a fault in an appliance causes too much current flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.

Fuses in plugs are made in standard ratings. The most common are 3A, 5A and 13A. The fuse should be rated at a slightly higher current than the device needs:

- if the device works at 3A, use a 5A fuse
- if the device works at 10A, use a 13A fuse

Cars also have fuses. An electrical fault in a car could start a fire, so all the circuits have to be protected by fuses.

## The circuit breaker

The circuit breaker does the same job as the fuse, but it works in a different way. A spring-loaded push switch is held in the closed position by a spring-loaded soft iron bolt. An electromagnet is arranged so that it can pull the bolt away from the switch. If the current increases beyond a set limit, the electromagnet pulls the bolt towards itself, which releases the push switch into the open position.

from http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/electricityworld/mainselectricityrev3.shtml

======================

## Additional resources

### How does a Residual Current Circuit Breaker Work?

### External resources

http://www.electronicsteacher.com/direct-current/physics-conductors-insulators/fuses.php

https://www.allaboutcircuits.com/textbook/direct-current/chpt-12/fuses/

https://en.wikipedia.org/wiki/Thermal_management_(electronics)

https://www.howequipmentworks.com/electrical_safety/

https://www.howequipmentworks.com/electricity_basics/

### ===========================================

## Learning Standards

**Massachusetts 2016 Science and Technology/Engineering (STE) Standards
**

HS-PS2-9(MA). Evaluate simple series and parallel circuits to predict changes to voltage, current, or resistance when simple changes are made to a circuit

HS-PS3-1. Use algebraic expressions and the principle of energy conservation to calculate the change in energy of one component of a system… Identify any transformations from one form of energy to another, including thermal, kinetic, gravitational, magnetic, or electrical energy. {voltage drops shown as an analogy to water pressure drops.}

HS-PS3-2. Develop and use a model to illustrate that energy at the macroscopic scale can be accounted for as either motions of particles and objects or energy stored in fields [e.g. electric fields.]

HS-PS3-3. Design and evaluate a device that works within given constraints to convert one form of energy into another form of energy.{e.g. chemical energy in battery used to create KE of electrons flowing in a circuit, used to create light and heat from a bulb, or charging a capacitor.}

## Emmy Noether

Emmy Noether

(article to be written)

Amalie Emmy Noether (1882 – 1935) was a German mathematician known for her landmark contributions to abstract algebra and theoretical physics. She was described by Pavel Alexandrov, Albert Einstein, Hermann Weyl, and Norbert Wiener as the most important woman in the history of mathematics. In physics, Noether’s theorem explains the connection between symmetry and conservation laws.

*

Articles

http://www.thephysicsmill.com/2014/03/09/international-womens-day-spotlight-emmy-noether/

*

## Magnetism MCAS topics

See the lesson here Kaiserscience -> Physics -> Electromagnetism -> “Magnetism-and-electricity”

text

MCAS Open Response: sample questions with full solutions

## MCAS questions

Which of the following forces allow a battery-powered motor to generate mechanical energy? (2014)

A. magnetic and static B. electric and magnetic

C. static and gravitational D. electric and gravitational

———————————————————

Which of the following statements describes an electric generator? (2013)

A. A magnet is rotated through a coil of wire to produce an electric current.

B. Electric potential in a rotating coil of wire creates a permanent magnet.

C. An electrical current causes a coil of wire to rotate in a magnetic field.

D. Forces from a permanent magnet allow a coil of wire to rotate.

———————————————————

———————————————————

This next one is from 2010

———————————————————

Which of the following would cause the galvanometer needle to move?

A. wrapping additional wire around the tube

B. uncoiling the wire wrapped around the tube

C. moving a magnet back and forth inside the tube

D. moving an aluminum block up and down inside the tube

———————————————————

### This next one is from 2009

Precise measuring instruments require shock absorbers to eliminate small vibrations that can affect the results of an experiment. One type of shock absorber that can be used is an electromagnet that repels a magnetic platform placed above it. Which of the following setups would provide the greatest lift to the platform?

## Scientific calculators < $10

This might seem amazing, but today one can purchase scientific calculators for less than $10.

http://budgetlightforum.com/node/34682

Learning Standards

MASSACHUSETTS CURRICULUM FRAMEWORK FOR MATHEMATICS

CONCEPTUAL CATEGORY: Number and Quantity

Calculators, spreadsheets, and computer algebra systems can provide ways for students to become better acquainted with these new number systems and their notation. They can be used to generate data for numerical experiments, to help understand the workings of matrix, vector, and complex number algebra, and to experiment with non-integer exponents.

Guiding Principle 3: Technology Technology is an essential tool that should be used strategically in mathematics education. Technology enhances the mathematics curriculum in many ways. Tools such as measuring instruments, manipulatives (such as base ten blocks and fraction pieces), scientific and graphing calculators, and computers with appropriate software, if properly used, contribute to a rich learning environment for developing and applying mathematical concepts. However, appropriate use of calculators is essential; calculators should not be used as a replacement for basic understanding and skills. Elementary students should learn how to perform the basic arithmetic operations independent of the use of a calculator.4 Although the use of a graphing calculator can help middle and secondary students to visualize properties of functions and their graphs, graphing calculators should be used to enhance their understanding and skills rather than replace them. Teachers and students should consider the available tools when presenting or solving a problem. Students should be familiar with tools appropriate for their grade level to be able to make sound decisions about which of these tools would be helpful.

Use appropriate tools strategically. Mathematically proficient students consider the available tools when solving a mathematical problem. These tools might include pencil and paper, concrete models, a ruler, a protractor, a calculator, a spreadsheet, a computer algebra system, a statistical package, or dynamic geometry software. Proficient students are sufficiently familiar with tools appropriate for their grade or course to make sound decisions about when each of these tools might be helpful, recognizing both the insight to be gained and their limitations. For example, mathematically proficient high school students analyze graphs of functions and solutions generated using a graphing calculator. They detect possible errors by strategically using estimation and other mathematical knowledge. When making mathematical models, they know that technology can enable them to visualize the results of varying assumptions, explore consequences, and compare predictions with data. Mathematically proficient students at various grade levels are able to identify relevant external mathematical resources, such as digital content located on a website, and use them to pose or solve problems. They are able to use technological tools to explore and deepen their understanding of concepts.

## Data needs an interpretation to have meaning

Lesson: “Data has no meaning without a physical interpretation”

Content objectives:

1. SWBAT to identify trends in data (apparent linear plots; apparent linear data plus noise; and simple harmonic motion.)

2. SWBAT to id

Thesis: raw data doesn’t tells us anything physical phenomenon. We always first need to know what physical phenomenon we are analyzing, before we can interpret it.

Tier III vocabulary: Simple harmonic motion

Launch: Students are given graph paper, and data. Plot the given ata points, and connect the dots in a way that they think is logical.

Question: Justify *why* you connected the dots in that way. Why not in some other way?

Direct Instruction/guided practice

Part A. Teacher instructions:

Print out a sine wave (attached.)

Draw a straight line across it, from upper right to lower left.

The line will intersect the sine wave at 7 points.

Overlay graph paper on top of this, and plot these 7 points.

Tag six more points from the sine wave, that are not on the original straight line.

These points should be at the wave’s maxima, minima, and zeroes, and other points.

Determine the Cartesian coordinates for them,

Give students graph papers, and at first, only 7 data points. Additional data points come afterwards.

If one were to plot only these 7 points, they would appear as a straight line. A naive reading of the raw data would lead one (mistakenly) to believe that we are studying some kind of linear phenomenon.Give examples of linear phenomenon.

One at a time, give new data points, ask them to re-draw their graph each time

Part A Student Instructions

Use the graph that you created for the Do now.

Add the additional data points to this graph.

What function (line, curve, etc) best fits all of this this data? (both old and new data points.)

Draw the line/curve that best fits.

Part B: Examples of data not involving motion: Size of objects from 10^1 meters, to 10^20 meters (human-size up to galactic structures.) The Scale of The Universe (interactive applet)

Independent /collaborative work:

Part A: Justify your choice: What real world motion would produce such a function? Think-Pair-Share

After the discussion, the teacher reveals what produces such data: SHM, Simple Harmonic Motion:

Summative question, tying this all together: Why couldn’t most students plot the data correctly, even after the final data points were added? Answer: Unless you know what kind of phenomenon you are studying, you have no idea whether the data is supposed to be linear, harmonic, exponential, etc. Data – bt itself – has no meaning without a physical interpretation.

Part B: Last night they built a data table for this part of the lesson. As we use “The Scale of The Universe” (interactive applet) they’ll fill in sizes of objects at all scales.

Closure:

Query multiple students: Where do you experience SHM in your own life?

Possible answers: Moving back-and-forth on a swing, pendulum of a clock, automobile suspension system

Homework:

Textbook: Physics: Principles and Problems (Glencoe)

Read Chap. 2, Section 1, “Representing Motion”, and Section 2, “Where and When? Coordinate Systems”

Write definition for highlighted “new vocabulary” words. Page 36. Section 1 Review, #1-4.

## Learning standards

A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012)

Dimension 1: Scientific and Engineering Practices: Practice 4: Analyzing and Interpreting Data.

“Once collected, data must be presented in a form that can reveal any patterns and relationships and that allows results to be communicated to others. Because raw data as such have little meaning, a major practice of scientists is to organize and interpret data through tabulating, graphing, or statistical analysis. Such analysis can bring out the meaning of data—and their relevance—so that they may be used as evidence.”