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University of Nebraska–Lincoln

Transportation Systems Engineering

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Lesson Overview
Lesson Title:
Pendulum inquiry

Mr. Philip Monroe (Primary)

Brief Description:
This lesson will use inquiry to explore the scientific method and periodic motion. It can be expanded to include conservation of energy and formulas for GPE and KE

Topics Introduced:
variables and scientific method

Transportation, Distribution, and Logistics Curriculum Framework Components Addressed:
Transportation Operations
Logistics Planning and Management Services
Health, Safety and Environmental Management
Suggested Grade Levels:
8th Grade
9th Grade
10th Grade

Standards Taught:
12.1.1 Science 2010
12.1.2 Science 2010
12.1.3 Science 2010

Lesson Information
Learning Expectations:

Students will be practicing their skills in solving problems, with multiple variables. They will also be learning to use the scientific method in a practical method.

Students should be able to explain that
1. ONLY ONE variable can be changed at a time
2. EACH VARIABLE must be changed at some point
3. The only variable that makes a pendulum change is the string length. This is a secondary expectation.

Plan Of Action:

Have the students record what THEY think the variable is that changes the motion of a pendulum. Compare this to results after the lab is done.

There are three variables, but remember to only change one at a time.

Complete a control run of the pendulum. Everyone will do the same control run. Everyone will start with a string length and bob mass of their own choosing.

Change only one of the variables at a time, keeping the other two the same as the control run, but change the variable twice. Your instructor will show you an example. You are attempting to isolate that variable that influences the frequency of a pendulum.

By examining your data, be able to prove to yourself which of the three variables, or combination of them, will change how fast a pendulum swings. Answer the questions, in cursive, on the following pages

Data Set Used:

Students will change one variable at at time, and fill out the data chart that is on the lab report. Students will record the Bob mass, the string length and the distance pulled back for each experimental run.

Materials Needed:

Well stocked school or program
1. Pole stand (used to hold a ceramic holder with bunson burner)
2. Pendulum stand (holds strings with twist screws)
3. Scale masses with hooks
4. Meter sticks
5. Fishing line or similar string
6. Hooks to hold mass (pendulum bob)
7. Stop watches
8. Calculators

A program that may not be as well stocked
1. Any device that string can be dangled from, that will allow the amount of string to be altered.
2. Rulers or meter sticks (please don't use inches)
3. Fishing line or similar string.
4. Tie the string instead of using hooks to the masses
5. Weights of some sort (washers, nuts, fishing weights) of various mass.
6. Students can use their own cell-phones as stop watches and calculators. Timers can also be accessed through the internet and projected on to a wall.

Preparation Period:

In a well stocked school, the preparation time will be about 25 minutes.

If a teacher needs to make the materials and supplies from scratch, the teacher may need one to two hours for preparation.

After the first time the lab is completed, and unless it is totally taken apart, preparation time can be as little as 10 minutes.

Implementation Period:

This inquiry laboratory is designed to be completed in one 45 minute period. Extensions will add on to the implementation period.

15 minutes to answer questions and graph (homework)
5 minutes to watch video of Tacoma Narrows Bridge collapse (off of youtube or similar site)
5 minutes to demonstrate pendulums
a. Compare bowling ball with 2 meter string to a 100-gram mass with a 2 meter string
b. Compare bowling ball with 2 meter string to a bowling ball with a .2 meter string (20 centimeter)
c. Compare bowling ball with 2 meter string (pulled back 10 cm), to a bowling ball with a 2 meter string (pulled back 100 cm)
10 minutes to have a competition of students to use the pendulums as a time keeping device

Unknown amount of time to consider this
A PENDULUM IS AT THE NORTH POLE. The pendulum will be swinging with a 90º change in direction each six hours, because the Earth is moving underneath it. This is easily demonstrated by starting a pendulum, and turning the base.

A PENDULUM IS AT THE EQUATOR. IF THE PENDULUM IS STARTED TO SWING IN THE EAST WEST DIRECTION; would the pendulum change its direction of swing because of the movement of the Earth?


Science, Math, Engineering and / or Technology Implications:

This lesson is a demonstration of the scientific method, and the solving of a problem using inquiry.

Pendulums use periodic motion, and are an excellent analogy and model for the frequency of action for bridges and buildings when energy is applied. This is especially important for windy conditions and any structure in a seismic event.

Unexpected Results:

Students come into the lab with a preconception that the distance pulled back, and the mass of the Bob are the variable that will change the pendulums motion. Some students will be so influenced by this misconception that they will fudge data until they get the desired result. They may also not complete the laboratory experiment because they think that they are doing it "wrong".

Considerations for Diversity in Education:

This lesson is specifically designed to be helpful for students along all parts of the spectrum of problem solving ability.

Students with little experience in multi-variable problem solving experience will need more direction, but they should see that one variable is changed at a time, and appropriate manipulation can be used to create a technological machine. The machine is, of course, a clock.

Students with more experience will need less direction, and graphing can be incorporated into the lesson plan, with the "x" axis being the independent variable, and "y" axis being the dependent variable. The "x" axis would be string length, and the "y" axis would be the cycle period or Hertz (not the same thing).

Students with math skills and deeper understandings could calculate the speed of the bob at different places, using the relationships between G.P.E. and K.E.

Students who need another (rare) level of challenge, could examine the changing movement of the two dimensional (perpetually swinging) pendulum as it interacts with the third dimension of the turning Earth. This is a level of challenge applicable to highly gifted students, but it is really interesting.

Lesson Files
Pendulum Experiment and Scientific Method
The inquiry method is used to explore pendulum motion, within the confines of the scientific method
[size: 40448] [date uploaded: Mar 18, 2012, 10:40 am ]

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