CP

## Pre-requisite

Algebra I (A) - grade of A or any math (CP) grade of C and any science (CP) - grade of C

## Course description

Experimental Methods
Lake Zurich High School
2006-2007
Mr. Agustin
phone: (847) 540-4618
email: brian.agustin@lz95.org
Website: www.lz95.org/lzhs/Science/index.html

If you were an apprentice carpenter; your first task would be to learn what tools you need in your toolbox and how to use them. How silly it would be to ask you to construct a table; craft a desk; or build a house if you have not yet learned how to use the carpenter?s tools!

In much the same way; you are an apprentice scientist in this course. My goal is to guide you to understand what tools are necessary to be a successful scientist and help you develop the techniques need to become skilled at using these tools. Experimental Methods is a laboratory based course that is designed to challenge students by developing the tools used in the physical sciences. The course prepares students for chemistry and physics by focusing on the refining of scientific skills such as measurement; graphing; analyzing data; solving mathematical expressions; scientific writing; and developing a scientific thought process.

What are the course objectives?
At the conclusion of this course; you should be able to?
? Collect; record; and interpret data by using appropriate scientific equipment.
? Apply the scientific method as a scientific problem solving tool.
? Research and evaluate the effects of a particular scientific breakthrough.
? Report; display; and defend the results of a scientific investigation.
? Use the technological design process to solve the design problem (propose; build; test; and modify.)
? Establish and practice safety rules during laboratory experiments.
? Assess the validity of a scientific claim.
? Demonstrate the difference between scientific inquiry as a process and technological design as an application.
? Investigate through experimentation the relationship between physical and chemical changes of matter.
? Apply the knowledge of physical and chemical changes to environmental issues.
? Investigate the relationship between mass; weight; and gravity.
? Evaluate methods of direct and indirect measurement.

What is required of me?
Simply put; students who enroll in Experimental Methods must be well focused and hard working. The course is highly technical and detailed oriented. As such; students need ample opportunity to practice the skills and techniques introduced during the course; these opportunities appear in the form of in-class practice; lab activities; and homework. The importance of completing these assignments cannot be overstated. NO LATE WORK WILL BE ACCEPTED (except when absent?see below)!

Where and when can I find you if I have questions?
I am generally available throughout the day and after school; but it is best to make an appointment. My office is in C115. I typically check e-mail each night around 9 p.m. You are welcome to ask questions of me this way.

What do I do if I'm absent?
It is your responsibility find out what you missed by checking your course schedule for assignments; talking to class members; coming in to see me; or e-mailing me from home. The entire manual can be downloaded from our Experimental Methods webpage so that you can do your homework even if you left your manual at school! If you miss a test; these can be made up Tues; Wed; or Thurs during any free period in the MST Resource Room.

You will be given one day to make up work for each day absent.

What do I need to bring each day for this class?
1. 1Ω - 2 inch 3-Ring Binder (to put your manual inside)
2. Pencils
3. Scientific Calculator (one with scientific notation)
4. Loose leaf paper
5. Three dividers (notes; handouts/quizzes; manual)
6. Ruler
7. A floppy disk and a memory stick (254MB) to save computer work done in class

How will my grade be determined?

Each unit will have a stamp sheet on which total points will be earned and recorded. Quarter grades will be determined by you points / points possible.

40% First Quarter
40% Second Quarter
20% Final
Grades will be determined using the below percentage scale?
97-100 A+ 87-89 B+ 77-79 C+ 67-69 D+
93-96 A 83-86 B 73-76 C 63-66 D
90-92 A- 80-82 B- 70-72 C- 60-62 D-

What advice do you have for me to be successful in this course?
? Since homework/labs make up half of your grade; success in this course begins with you doing your homework and labs on time.
? When you have questions; you?ll need to ask. I want you to be successful as much as you want to succeed?but the responsibility is on YOU to ask when you have questions.

I look forward to a great year together.

Mr. Agustin

Experiment 13: The Law of the Lever - Archimedes Principle
Introduction:
The first gravitational balances used were equal-arm balances. A standard unit of mass was placed on one side of the balance; and the unknown mass was placed on the other side. Between the two was a pivot point or fulcrum. The distance to each mass from the fulcrum was equal; thus the term equal-arm balance. What would happen if the distance from the fulcrum to the masses was varied? For example; when you played on a see-saw in your younger years; you might have wanted to see-saw with someone who was twice your mass. You probably solved the problem by adjusting the fulcrum of the see-saw.

In the first part of this experiment; you will determine a relationship between the mass and distance on of two objects located on opposite sides of a piece of wood. The second part of the experiment will expand this relationship to include two or more masses on each side of the fulcrum. In the third part of the experiment; you will use the relationship from above to indirectly calculate the mass of the piece of wood you used as a balance arm. The fourth part of the experiment will concentrate on measuring the mass of the balance directly and calculating a percent error for your indirect measurement.
Procedure:
Part A
Secure a test tube clamp approximately 30 cm above the table top on a ring stand. Tie a loop in one end of a small piece of string and then tie the other end around the center of the balance arm. Hook the open loop onto the test tube clamp so that your balance arm hangs above the bench with the hooks pointing down. Adjust the position of the piece of string until your balance is level.

Add a 100 gram mass to the second hook from the fulcrum. Do the same to the right hand side of the balance arm. The balance arm should then be balanced. If not; adjust the location of the fulcrum until the balance arm is very nearly balanced.

Using the table on the following pages as a guide; place masses at the appropriate locations on the balance arm. Add just enough mass to the right side to level the balance arm. Look over the data and try to figure out a pattern. From the pattern you can develop a mathematical equation that relates the mass and distance on one side to the mass and distance on the other. For your last trial; test your equation by placing a mass at any one hook on the left side and calculating the distance or mass on the other side.

Trial
# Distance to
mass1 (hooks) Total mass
of mass1 (g) Distance to
mass2 (hooks) Total mass
of mass2 (g)
1 1 200 2
2 1 200
3 1 200
4 2 300
5 4 500
6

Part B
In this part of the experiment; you will place several masses on the left at different distances from the fulcrum and also place several masses at various distances on the right. Look at the data table. Each trial will indicate how many groups of masses should be placed on each side of the fulcrum. If there are two blanks for distance on the left; you should hang two groups of masses; etc. After observing your data; revise your equation from Part A so that it will correctly explain the data when there is more than one group of masses on each side.

Trial
# Mass
ML1 Dist.
DL1 Mass
ML2 Dist.
DL2 Mass
ML3 Dist.
DL3 Mass
MR1 Dist.
DR1 Mass
MR2 Dist.
DR2
1 100 1 200 2 500
2 300 2 100 4 4
3
4

Part C
Remove your balance from the pivot point and place the dowel rod through the hole that is not at the center of gravity. Hang masses on your balance until it is balanced. Hang all of the masses on one hook. If your balance does not completely balance with masses that you have; take a nickel; which has a mass of 5 grams; and place it on the top of the balance. Slide the nickel across the top until the balance is balanced. (Measure the distance to the nickel in hooks and fractional hooks.) Make a sketch of your set-up in your data. It first appears that your balance has no mass on the other side. Incorrect! (Hint: Where is your center of gravity of balance? What is the definition of the center of gravity?) Calculate the mass of your balance. Record this in your data along with the equation that you used to solve for the mass.

Part D
Measure the mass of your balance using a gravitational balance and calculate your percent error.

Post Lab Questions

1. Explain why the mass of the balance arm was irrelevant in Part A of the experiment.

2. Identify two practical applications of the law of the lever.

3. Identify any major sources of error in part C of the experiment.

4. If the first equation from part a specific equation or a general equation; that is does it apply to every balance or just particular type of balance. If it?s a specific equation what are the limitation of the equation?

United States

Illinois

Lake Zurich

## High school

Lake Zurich High School

300 Church St.

60047

Lab Science

Yes

## Approved competency code

• LINT
• Integrated science

No