Physical Science Period: Name: Paper Towel Lab Date: All answers (other than numbers in the data table) should be in complete sentences!! Lab problem: We will be testing and comparing the absorbency of various brands of paper towels Pre-lab 1. What is the precision to which we will measure our water, assuming that the graduated cylinders have 1ml divisions? Why is that? We can measure to one more level of precision, since the measurements are in 1 ml, we can estimate to the 0.1 ml 2. Given what you said above, give the volume of water in the graduated cylinder to the left to the correct level of precision: The measurement is approximately 52.7ml. 3. What is your hypothesis about which brand will be the best and why? Any hypothesis stating what paper towel brand would be the most absorbent and why you thought that 4. What is the manipulated variable in our experiment, and how do you know? The manipulated variable is the brand or type of paper towels, because that’s the variable we are changing. 5. What is the responding variable in our experiment, and how do you know? The responding variable is how much water is absorbed, because that’s what we’re measuring in response to the change in type of towel. 6. List 4 controlled variables (there are way more than 4 possible) and what numbers or methods would you choose for each (we will decide on values to use as a class later). Variable (or description of controlled variable) Value or method 1. 2. 3. Any 4 variables that need to stay the same between trials to ensure a fair comparison 4. Why is it important to control these variables? with 4 corresponding values/methods If we don’t keep these values the same between all tests, our test’s validity is gone, and we don’t have a fair comparison between trials. Class controlled variable values discussion: Period 1 7. Listen to the class discussion about the controlled variables. For the controlled variables, what did we decide to use as values in this class? Variable (or description of controlled variable) Value or method 1. 2. 3. 4. 5. 6. 7. 8. 9. Class controlled variable values discussion: 7. Listen to the class discussion about the controlled variables. For the controlled variables, what did we decide to use as values in this class? Variable (or description of controlled variable) 1. 2. 3. 4. 5. 6. 7. 8. 9. Value or method Class controlled variable values discussion: 7. Listen to the class discussion about the controlled variables. For the controlled variables, what did we decide to use as values in this class? Variable (or description of controlled variable) Value or method 1. 2. 3. 4. 5. 6. 7. 8. 9. Class controlled variable values discussion: 1. Listen to the class discussion about the controlled variables. For the controlled variables, what did we decide to use as values in this class? Variable (or description of controlled variable) 1. Amount of time to absorb water 2. What kind of surface or method Value or method 10s Put in 400ml beacker 3. Amount paper towel used 20.5 x 15.5 cm 4. Starting volume of water 40 m 5. How it gets water put in beaker 6. How paper towel is folded/wadded fold in ½ 4 times, push with pencil 7. 8. Data table. Make sure you express your data to the level of precision specified Final Volume left in beaker(ml) Initial Volume in Average of Brand Trial 1 Trial 2 Trial 3 beaker (ml) trials Average ml absorbed by the paper towels (show your work) BHS Bounty Brawny Brightly Kirkland Pantry Essentials Sparkle Thirsty Viva Data table completed with: At least 1 trial for each paper towel type Average Amount absorbed, with work shown, for each and values All measured data recorded to a precision of 0.1ml. Analysis: make a graph (of the appropriate type) comparing the average amount of water absorbed for the different brands of paper towels. Include all the qualities of a good graph. Make sure axes are in standard order Bar graph Meaningful Title Manipulated variable on x-axis paper towel brands axes labeled : x paper towel brands y water absorbed (ml) even increments on axes be large enough to be seen about at least ½ space allotted drawn using a straight edge Conclusions: Answer in complete sentences. 1) Which type of paper towel actually absorbed the most water? How did this compare to your original hypothesis? Described which paper towel absorbed the most water and how that compared to your predictions in complete sentences. 2) What are some other factors besides absorbency that are important when considering a particular paper towel brand? At least two other factors (e.g. Strength of the paper towel while wet, speed in absorbing water, durability of the paper towel when rubbed, number of paper towels per roll, etc.) 3) Choose one of the factors you listed in conclusion question #2, determine how you would test it, specifically mentioning what your manipulated, responding, 4 controlled variables would be, as well as a brief process to test it. Item from conclusion question 2 you’re testing: listed here type of towel ;Responding variable: item listed in #2 Manipulated variable: Any 4 controls Cannot be brand Controlled variables: or responding var process to test: List of steps 4) The cost of the paper towels (when bought in bulk of 6 or more rolls) is as shown below. Brand Plain (BHS) Bounty Brawny Brightly Kirkland Pantry Ess. Sparkle Thirsty Viva Price per roll (in bulk if available) $7.19 $1.24 $1.33 $0.83 $1.41 $0.99 $1.27 $0.92 $1.40 Approximate number of same-sized towels per role 600 66 70 52 80 60 65 70 44 Approximate cost of each same-sized paper towel 1.18¢ 1.87¢ 1.90¢ 1.60¢ 1.77¢ 1.65¢ 1.95¢ 1.31¢ 3.12¢ Using your data and the information to the left, does the cost of the paper towels directly correlate to the absorbency (is the most expensive the most absorbent, 2nd most expensive the 2nd most absorbent, etc.), if not what relationship is there, if any? Typically there is no real relationship, as Viva are the most expensive per paper towel and might absorb the most water, and BHS paper towels are the cheapest per paper towel and do absorb the least, but the rest are relatively random Ranking by price and absorbency would be: $ Per 1 Per 3 Per 5 Per 6 BHS Thirsty Brightly Pantry Kirkland Bounty Brawny Sparkle Viva BHS Pantry Ess. Sparkle Brightly Thirsty Viva Kirkland Brawny Bounty BHS Pantry Ess. Brightly Sparkle Kirkland Thirsty Brawny Bounty Viva BHS Pantry Ess. Brightly Sparkle Brawny Thirsty Kirkland Viva Bounty BHS Pantry Ess. Sparkle Brightly Thirsty Kirkland Brawny Bounty Viva 5) Using the information given in question 4 and your own data, divide the average ml absorbed by cost per towel to get ml absorbency for each cent of cost, this will give the ratio of absorbency to price for each of the brands. Summarize calculations in the table below (Show your work!!): BHS Bounty Brawny Brightly Kirkland Thirsty Pantry Essentials Sparkle Viva Absorbency for each cent of cost (Show work) Which paper towel has the most absorbency for each cent of cost? What does that mean? The paper towel with the most absorbency for each cent of cost is Thirsty which means it absorbs the most for its cost (most worth the money, if absorbency is primary factor for buying) 6) Why might the school use the plain white towels rolls instead of another brand? Hint, look at the tables you generated above as well as other tables given to you in conclusion question 4. Give at least two different ideas. The school uses the white paper towels because They are the cheapest overall per towel, so are most cost effective They have the most (by far) number of paper towels per roll so they don’t have to be replaced very often and will last way longer than other paper towels, saving man power needed to change more often. Their absorbency per cent of cost is actually on par with or better than some of the name brands. They fit into the standard, lockable dispensers, so they can be more easily regulated. They are thinner and take up less landfill space.
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