Chapters

 Page 1

This text is meant to accompany class discussions. It is not everything there is to know about uniform circular motion. It is meant as a  prep for class.

Click for the questions that go with this reading
Lab Components

These components are adopted almost word from word from Dolores Gende.

1 Lab Investigation Question

The problem or task to be investigated is written as a question by the student. It provides the overall direction for the laboratory investigation and must be addressed in the conclusion. This becomes the objective of the lab.

A good expeiment is validated through repitition. The instructions, the data and it's analysis need to be clearly written.

There are three types of variables:

• Control variable: This is a measurement or number that does not change through out an experiment.
• Independent variable: This is a variable set by the experimentor.
• Dependent variable: This is an outcome from the experiment.
 Example 1 - Variable types Ice is added to 500 ml of water at 25°C in a room with a temperature of 20°C. The time is takes for the ice to reach 5°C is measured. During each trial a different amount of ice is added. Identify each type of variable.

 For each short experiment, identify the dependent, independent and control variables. 1 (Example) Every day the relative humidity is measured at 1:00 PM on the roof of the school. 2 The speed of a car is recorded every mile the car travels from home. 3 A lady bug is placed on the edge of a cd.  Every 1/10 of a second the bugs facial expression is examined. 4 Every day after lunch time the amount of trash on the breezeway is collected and weighed. 5 A different year of the same model car is driven into a unmovable cement wall, front first, at 30 mph. After each collision the, distance the front is smashed in is measured. 6 The height a super ball bounces is measured after each of its bounces. 7 In a cold study the researchers measure the amount of nasal discharge every 6 hours from an infected the patient. 8 The time it takes to for a snail to travel every foot of distance is recorded. 9 The number of students in each teacher’s class at a school is counted every period. 10 A car speeds up on a highway from rest. Whenever the car’s speed increases by 10 mph the time is recorded. 11 Every year the number of car commercials during the superbowl is recorded. 12 A model rocket is launched 10 times.  Each time the same rocket is launched with motors of indetical power, its maximum height is measured and recorded. 13. In seperate trials, various amounts of sugar is added to 100 ml water. the weight of sugar that crystalizes is measured. 14. The speed of the same child is measured on the same playground slide. But each time the child slides down, she slides on a different piece of fabric.

2 Equipment and Equipment Setup

• A list of all laboratory equipment used in the investigation
• A detailed and labeled diagram to illustrate the configuration of the equipment.

3 Step-by-Step Procedure

• Neatly explained in a numbered sequence.
• Do not use the word, " I, you, it, and, thing" in your instructions.
• Keep is simple with a bulleted list.
• Include at least one picture in the procedure. You can draw it using the draw tools in Google Docs or you can use your computer's built in camera.
• Identify and name all experimental variables.
• If you use a varibale in a calculation define what it measures and its units.
• Briefly describe how the independent variable is controlled.

Hint: Your audience is not necessarily composed of Physics types! Someone who was not present during the lab should be able to understand how the experiment was performed and be able to reproduce the results by reading your procedure.

 Example Procedures Wrong Right I placed the car against the back of the track. I wound it up all the way. You measure to the end of the track. You let go of the it. Measure from the end of the track, to where the bag begins. Wind up the car all the way. (Until you hear a loud clicking sound.) Place the car against the back of the track with its front bumper behinds the starting line. Begin timing when the car is released.
 The red words highlight some of the changes. The first thing that is different is the order. It makes more sense now. The words "I, you, and it," are removed. The last step adds a little more detail.

4 Data

• Include a list of variables measured once. -Not in the data table.
• Include a data table that shows all the variables that were measured multiple times.
 Note: Only include measured quantities. (If you need to use a calculator to get a quantity, then it does not go here.) Take all measurements in SI units unless otherwise allowed.

Example
In this experiment a car was sent along a track 12 times. The length of the track was measured one time and the time was recorded 12 times. The average velocity was also calculated for each trial.

Data section of the lab looks like this.

• Distance the car traveled along the track : 1.505 m
 Trial number Time to travel along the track            (s) 1 0.79 2 0.81 3 0.77 4 0.85 5 0.77 6 0.75 7 0.83 8 0.81 9 0.70 10 0.73 11 0.82 12 0.78

Continued on the next page

by Tony Wayne ...(If you are a teacher, please feel free to use these resources in your teaching.)