Physics C Mechanics
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Lab Information Overview

ALL STUDENTS MUST READ THROUGH THE FOLLOWING OVERVIEW PRIOR TO PERFORMING ANY TYPE OF LAB ACTIVITY IN THIS COURSE

There are six parts to this overview:

1. A list of equipment needed to perform the hands-on lab activities for this course is shown below. Read through this list carefully to make sure that you have all the equipment prior to getting to the lab activity. Although almost all of the equipment can be found in a typical home, some of the items may need be purchased at a neighborhood store or an online retailer like the ones suggested. If you want to order this equipment online, please give yourself time for shipping.

2. An important reading assignment on the nature of scientific practice.

3. A quick look at the concept of significant figures.

4. A six minute video on graphing.

5. Information about keeping a lab notebook.

6. A quiz on the material in this activity.

List of Equipment:

Unit

Lab

Materials

1

Kinematics

Note: Steel ball bearings are available at most hardware stores.

Current Price: Less than $1.00 each

  • Heavy marble (steel ball bearing preferred)
  • Two long   pieces of wood (preferably two meter sticks)
  • Books or a box of Kleenex
  • Ruler (preferably a meter stick)
  • Protractor (optional
  • Stopwatch

2

Coefficient of Friction

  • Long piece of smooth wood (ex: a bookshelf)
  • Small block of wood
  • Protractor to make angle measurements (or a ruler to make length measurements)
  • Books to help make an inclined plane with the long piece of wood
  • Several pieces of notebook paper
  • Tape

3

Uniform Circular Motion

  • The body tube from a ball point pen
  • String
  • 10 to 15 pennies (1983 or newer)
  • 15 quarters (1965 or newer)
  • Masking tape
  • Ruler
  • Stopwatch
  • Safety glasses

4

Conservation of Momentum
 
Note: The entire ramp system can be purchased online at   Wards Science.
  https://www.wardsci.com/store/catalog/product.jsp?catalog_number=160031

Current Price: $19.10

  • Two heavy spheres (steel spheres preferred)
  • Plastic ruler
  • Piece of wood onto which the ramp can be fastened
  • Books
  • Tape measure or a meter stick
  • A plumb line (string with a weight attached)

5

Angular Motion

  • Several heavy glass marbles and several steel ball bearings of various sizes
  • Several different sized cans of soup
  • An empty spaghetti sauce jar
  • A new (thick) roll of masking tape or duct tape
  • A Long piece of smooth wood (ex: a bookshelf)
  • Books to help make an inclined   plane with the long piece of wood
  • Tape   measure or a meter stick
  • Stopwatch

6

Resonance

  • String or sewing thread
  • Two small objects with a hole. (For example: metal nuts or washers)
  • A stopwatch

7

Kepler’s Laws

  • Graph   paper
  • A ruler
  • A protractor

 

 The Nature of Science
     The practice of science has a long and illustrious history. Science, in the western world, is generally thought to have begun in ancient Greece with the so-called pre-Socratic philosophers. Thales (624 - 546 BCE) is often cited as an important example as he proposed, among other things, that water was the single material on which all other materials are based. The Greeks were the first to ask, and attempt to answer, important questions about the nature of the universe without dependence upon mythological explanations.

     The famous Greek philospher Aristotle (384-322 BCE) is credited as a pioneer in such diverse areas of academic interest as biology, geology, ligusitics, ethics, and many others, but most importantly for us, physics. Aristotle was a student of Plato and a teacher of Alexander the Great. His influence stretched out over two thousand years. Of particular interest to us is his geocentrism, the notion that the Earth is positioned at the center of the universe. As we will see, the ideas of Aristotle were eventually replaced by those of Isaac Newton (1642 - 1727) as the best explanation of the workings of the natural world.

     Newtonian mechanics differed drastically from Aristotle's in many ways, not the least of which is the notion of heliocentrism, or a sun-centered sysytem. Heliocentrism was promoted by several scientists prior to Newton's day (Copernicus, Kepler, and Galileo, for example), but it wasn't until the publication of Newton's famous text, Philosopiae Naturalis Principia Mathematica that humans began to see the universe as a giant mechanism. Newton's ideas are, however, now seen as an accurate description of only the medium-sized, slow-moving objects in our world. In order to gain an understanding of the sub-atomic world, or of the universe at large, scientists now turn to Quantum Theory and Einsteinian Relativity.

     Please don't view the process of new scientific theories replacing old ones as a weakness of the scientific enterprise. In fact, it is a strength of science that changes are made as new and confusing data become available.

     The changes in our scientific view of how the universe behaves has been the topic of a great deal of work in an academic area called "Philosophy of Science." For example, in 1962, with the publication of The Structure of Scientific Revolutions, the American author Thomas Kuhn coined the term "paradigm shift" to describe the times in history when the "normal" science of the day is replaced by a new and more explanatory science. Kuhn's broad background as a physicist, historian, and philosopher allowed him to identify the "non-linearity" of the scientific enterprise by showing how new paradigms are not built on old ones, but are instead prompted by anomalies in research that can eventually produce new theories that are drastically different from the old ones. The old and the new are not reconcilable. Additionally, Kuhn claimed that scientific truth is attained through a community of expert scientists and has a social component.

     The community aspect of the scientific endeavor is therefore an important part of the "practice of science." Educational researchers have recently promoted the idea that science students need to practice science in the classroom in the same way that scientists practice in the real world. That is why many of the activities you will be asked to perform in this course are "Inquiry-Based." That is, they are self-guided as much as possible, in the same way that natural curiosity guides the work of actual scientists in the field. Scientists are part of a community in which creators of claims elicit responses by critiquers of claims. The critiques may prompt new claims followed by further critique. This back and forth activity is an essential part of the way progress is made. The ultimate arbiter of scientific truth is the natural world, but the notion that science is socially-based helps to guide the understanding of science and the activities that should take place in the science classroom.

     The College Board has emphasized the importance of these ideas by publishing the following on pages 27-28 of the Teacher's Manual for AP* Physics 1 and AP* Physics 2:

"Throughout the study of the history and philosophy of science, there are 10 key points that have emerged about the development of scientific knowledge over time. In total, these points lead to one key conclusion: science is not a body of theories and laws but rather an approach to understanding observations that allows us to make sense of the world around us. If we think about these key points, they can help us understand the reasons for using inquiry in the physics laboratory.

These key points about the nature of science (as modified from McComas, 2004) are:

1. Scientific knowledge is tentative but durable.

2. Laws and theories serve different roles in science and are not hierarchal relative to one another.

3. There is no universal step-by-step scientific method.

4. Science is a highly creative endeavor, grounded by theory.

5. Scientific knowledge relies heavily, but not entirely, on observation, experimental evidence, rational arguments, creativity, and skepticism.

6. Scientific progress is characterized by competition between rival theories.

7. Scientists can interpret the same experimental data differently.

8. Development of scientific theories at times is based on inconsistent foundations.

9.There are historical, cultural, and social influences on science.

10. Science and technology impact each other, but they are not the same."

     The importance of lab activities in this course is supported by the aforementioned comments. For students using the resources at Physics Prep, the lab activites are most likely done by a single student carrying out an investigation. The lab notebook is thus an important way to eventually share the findings of investigations with others and receive feedback. Please follow the guidelines shown below so that your work can be shared in an organized and clear manner.

Measurement and Significant Figures

     When a scientist makes a measurement she uses a measurement device that will allow for a set level of accuracy that depends upon the physical characteristics of the device.  For example, look at the ruler being used to make the length measurement below.  One can say for sure that the measurement is greater than 11.6 cm, but the second decimal place in the measurement would only be a guess.

 

     The number of significant figures in a measurement represents all the digits that are known for sure PLUS one digit that is a guess.  The measurement made above might then be 11.65 cm.  But it would still be a valid measurement if someone used this ruler and claimed that the measurement was 11.64 cm.  Each of the measurements contains four significant figures.

     The College Board expects students who take the AP* Physics exams to understand the role of significant figures in measurement and to be able to determine the number of significant figures in the answers to problems involving the multiplication, division, addition and subtraction of measurements.  Since students taking this course are expected to have already taken a chemistry course, wherein the concept of significant figures should have already been covered, the rules below should act as a reminder of how significant figures are used...not as a tutorial.  If you want to see more information on significant figures click here to find an entry on Wikipedia.

     A quick note regarding significant figures and unit expression...you will notice that attention to significant figures is not always a high priority when computations are done during the presentations for this course.  Reasonableness in rounding is the rule when the concept being described is more important than attention to significant figures.  In other words, if the presentation is about magnetism, all the work shown will exhibit reasonable rounding in computations but not always strict adherence to the rules of significant figures.  Additionally, much of the work done will only show the units in the final answer of the calculation rather than in each step along the way.  Again, priority is given to efficiency in learning the concept at hand rather than making the problem look busy with unit notations.  

The rules that you should know in this regard are are follows:
1. All non-zero numbers are significant.
2. Zeros within significant digits are always significant. (Ex: 809 has three significant figures)
3. Zeros that are "place-holders" are not significant. (Ex: 0.0082 has two significant figures)
4. Trailing zeros that aren't needed to hold the decimal point are significant. (Ex: 20.00 has four significant figures)
5. When measurements are added or subtracted, the answer can contain no more decimal places than the least accurate measurement. (Ex: 21.47 + 1.1 = 22.6)
6. When measurements are multiplied or divided, the answer can contain no more significant figures than the least accurate measurement. (Ex: 5.156 x 2.3 = 12 because there are only two significant digits in one of the measurements being multiplied)
7. When answers are rounded off it is generally acceptable to round up if the last digit is 5 or greater and round down if the last digit is less than 5. Different sources may site different rules in this regard.

(You might want to print this information and place it in a binder for future reference)


Introduction to Graphing:



How to Keep a Lab Notebook:

Having a record of your labwork is a very important product of your work in this course.  The best lab notebooks are hard cover and bound, but any spiral bound notebook will suffice.  For each lab activity you should show the following in the lab notebook:

1. The title of the lab activity
2. The date the lab activity was performed
3. The goal(s) of the lab activity
4. A description of the lab activity (procedures, sketches, pictures, etc.)
5. Data collected in the lab activity
6. Analysis of data (graphs and sample calculations)
7. Analysis of error (when appropriate)
8. Conclusion(s) (Did you achieve your goal(s)...why or why not?)

The lab report should be done neatly and completely in the lab notebook so that any university officials that ask to see your reports would be satisfied regarding the lab component of your work in physics.

Finally, lab safety should be of utmost importance whenever a scientist performs a lab activity. Please do not use any of the equipment called for in this course in any way that is not safe. Follow all instructions regarding the use of any lab equipment that can cause injuries to you are anyone else in the vacinity of your lab work.

Take the Quiz
Click here to take the quiz after you have carefully read all of the material above. 

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