LABORATORY NOTEBOOK

Organization of lab notebook Keep a table of contents at the beginning of the notebook(about 2 pages) For each lab, start with the printed lab handout from teacher (tape/glue it) Then include the laboratory report completed according to the following format:

Friction Can Be a Real Drag 1. Title Place it on the top of the first page Write the name(s) of the person(s) doing the experiment Date of when the experiment was performed Friction Can Be a Real Drag

What are the main reasons you are performing this experiment? 2. Objective/Purpose What are the main reasons you are performing this experiment? Be specific...don't just restate the title or copy the generic objectives from the given lab packet or a textbook One or two sentences

In this laboratory experiment, I will 2. Objective/Purpose In this laboratory experiment, I will determine how does the force of friction (Fk) depends on the force of gravity (Fg) on an object when the object slides over a “smooth” horizontal surface and... determine how Fk varies with the area of contact between two smooth, flat surfaces when all other factors are controlled

3. Equipment A bulleted list of all the materials and equipment you will use in this experiment

3. Equipment Wooden blocks Spring balance Ruler String

Do not include lengthy, detailed directions. 4. Procedure In your own words, write a brief summary of the procedure in paragraph format Do not include lengthy, detailed directions. A person who understands physics should be able to read this section and know what you are doing

(You can also include a picture) 4. Procedure I first determined the mass of each wooden block using a spring balance I measured the force of kinetic friction of one block, two blocks, three blocks, and four blocks stacked on top of each other (You can also include a picture)

4. Procedure I measured the force of kinetic friction of the wooden blocks arranged the way so the surface area of the contact between the blocks and the surface was doubled, tripled and quadrupled (while keeping the force of gravity of the blocks constant)

All the data tables MUST have titles, quantities and units Record all the measurements and observations you made during the lab and put them into data tables All the data tables MUST have titles, quantities and units Do not erase when recording data; simply draw a single line through a mistake and record the new value next to it.

All the data tables MUST have titles, quantities and units Record all the measurements and observations you made during the lab and put them into data tables All the data tables MUST have titles, quantities and units Do not erase when recording data; simply draw a single line through a mistake and record the new value next to it.

Force Of Sliding Friction Of Wooden Blocks 5. Data Table 1: Force Of Sliding Friction Of Wooden Blocks

Force Of Friction as the Surface Area is Varied 5. Data Table 2: Force Of Friction as the Surface Area is Varied

6. Analysis and Results DO the calculations and put the results into new tables Do the graphs either by hand on the graph paper or by using MS Excel Each graph MUST include title, appropriate labels, quantities and units Determine sources of error and calculate absolute and relative error

Calculations for the slope of the line: slope = coefficient of kinetic friction= Fk2 – Fk2 = .... Fg2 – Fg1 Table 3: Determining the coefficient of kinetic fiction Fk1 (N) Fk2 Fg1 Fg2 Slope = Coefficient of kinetic friction Determining the coefficient of kinetic fiction Fk (N) Fg(N)

ABSOLUTE and PERCENTAGE (RELATIVE) ERROR If you want to compare how ACCURATE your measurement in a lab was to the accepted (known) value of whatever you measured For example: You found out that the Coefficient Of Kinetic Friction was 0.21 How accurate was your measurement to the “real” value for coefficient of the kinetic friction between the wooden block and the desk??

ABSOLUTE and PERCENTAGE (RELATIVE) ERROR How accurate was your measurement to the “real” value for coefficient of the kinetic friction between the wooden block and the desk?? You found out that the Coefficient Of Kinetic Friction (Experimental Value) 0.21 The Coefficient Of Kinetic Friction from a textbook or the internet (Actual Value) was found to be 0.29

ABSOLUTE ERROR = |0.21 – 0.29| = |0.08| = 0.08

PERCENTAGE (RELATIVE) ERROR X 100% = |0.21 – 0.29| 0.29 X 100% = 27.5862069 % ≈ 28 %

8. Conclusion Data is summarized Any derived relationships are mentioned Relate data to your hypothesis/purpose Reference your results Do the data and the results support your hypothesis/purpose? Explain, if you did the same experiment in the future, how would you avoid experimental errors?

Based on my experiment, it was found out that 8. Conclusion Based on my experiment, it was found out that the force of friction between an object and a smooth horizontal surface is depended on the force of gravity(weight), AND it is independent of the surface area of contact between the object and the surface. The reasons for #1: It was determined that when Fg was increased Fk also increased always by the same factor. This factor is µ, and its value was found out to be 0.20 (see Table 1 and 2). This value represents about 28% error when compared to the actual value (taken from the textbook). The reasons for #2: It was determined that when the contact area between two smooth surfaces was increased, Fk stayed the same meaning that Fk is independent of the surface area of an object and a surface (see Table 3). The large percentage error could be due to poor precision of the measuring equipment (spring scales) as well as due to unevenness of the wooden blocks that were used in the experiment. To avoid such a large error in the future, a digital scale and high quality blocks could be used.