CAS LF 111 Study Guide - Quiz Guide: Wordpress.Com
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please use the following information to answer questions 1-6
Imagine you have graduated and have just gotten a job in a fictionalized version of Paducah, KY, home of the world famous Dippin' Dots (Links to an external site.)Links to an external site.. You got the job by pitching a truly marvelous idea: The Grand Cone-yan, an ice cream festival as grand as any Court Days (Links to an external site.)Links to an external site. or Apple Festival (Links to an external site.)Links to an external site..
The centerpiece of the festival is a 10 foot tall ice cream cone filled with local ice cream dots.
The day before the festival the contractors have brought the truck of ice cream, and begin to fill the cone. After only a single minute, there is a foot of ice cream in your frozen glass cone. Since the entire cone is only 10 feet tall, you decide to come back in 10 minutes to witness the final filling.
You are shocked when you return to find the cone has only been filled to the 2 foot mark! (The worker politely corrects you to say it is actually 2 feet and 2 inches.) You give it another 10 minutes, but the cone is only 2 foot 9 inches filled.
Not knowing what else to do, you make a spreadsheet of the progress.
Time (minutes) | 0 | 1 | 10 | 20 | 30 | 60 | 120 |
---|---|---|---|---|---|---|---|
Height (feet, inches) | 0' 0" | 1' 0" | 2' 2" | 2' 9" | 3' 1" | 3' 11" | 4' 11" |
You wonder why they have slowed down so much, so you keep checking in every hour.
Time (hours) | 1 | 2 | 3 | 4 | 5 | 6 |
---|---|---|---|---|---|---|
Height (feet, inches) | 3' 11" | 4' 11" | 5' 8" | 6' 3" | 6' 6" | 6' 11" |
After six hours you are worried the entire festival might fail, but you won't give up! You keep spreadsheeting.
Time (hours) | 7 | 8 | 9 | 10 | 11 | 12 |
---|---|---|---|---|---|---|
Height (feet, inches) | 7' 4" | 7' 8" | 7' 11" | 8' 3" | 8' 6" | 8' 9" |
After 12 hours, you take a quick trip home to change clothes, and return to your spreadsheeting.
Time (hours) | 13 | 14 | 15 | 16 | 17 | 18 |
---|---|---|---|---|---|---|
Height (feet, inches) | 8' 11" | 9' 2" | 9' 5" | 9' 7" | 9' 9" | 10' 0" |
Finally, late in the night, around 3am, it is complete. Your masterpiece. The Grand Cone-yan. But why did it take so long? It took a lot longer than 10 minutes. Why did the workers slow down so much? The first minute finished the first foot, but three feet took 30 minutes instead of 3 minutes. And now it's 3am!
The workers say that they filled at a steady rate of 13 gallons per hour, and that any faster would run the risk of drain freeze.
Your responses
1. What is wrong with the following argument?
If you really did 13 gallons per hour, then the 10 foot cone should have only taken 10 / 13 = 0.7 hours, less than an hour tops.
2. What is wrong the following question?
How do you convert gallons into feet?
3. Find an authoritative source for the volume of a cone. Give the formula and explain what each part of the formula means in this problem.
4. Most formulas will have both radius and height. Find a reasonable source for the relationship between the radius and height of an ice cream cone. Give an expression like
R = H
5. Calculate the volume of the cone using your formula. At a constant rate of 13 gallons per hour, how long should it have taken to fill up?
You may use the approximate formula V=0.02908882 h3 if the formula you discovered does not match at all.
6. There should still be a discrepancy between the V=0.02908882 h3 and the spreadsheet. Can you explain what likely happened?
- Use the pipette to fill the test tube with approximately 1.5 mLof water.
- Move the temperature marker on the thermometer down to the -10°C mark.
- Place the thermometer inside the test tube. The marker shouldbe located at the very top of the test tube to prevent thethermometer from wiggling around. If not, adjust itaccordingly.
- Place the thermometer and test tube into a 250 mL beaker sothat the test tube can rest upright.
- Put the beaker with the test tube and thermometer in a freezerand allow approximately one hour to completely freeze and reach atleast -5 °C. If the temperature is at least -5 °C, move on to thenext step. If not, wait for the temperature to drop before movingon to the next step.
- Take the beaker and test tube with thermometer out of thefreezer.
- Record the temperature on the thermometer in Table 2 and makean observation about the state of the water.
- Repeat Step 6 every five minutes for thirty minutes.
Table 2: Temperature of Frozen Water over Time
Time (s) | Temperature (°C) | Observation |
0 | ||
5 | ||
10 | ||
15 | ||
20 | ||
25 | ||
30 |
Boiling Water
- Fill a pot halfway with water and place it on the stovetop.
- Place and hold the thermometer in the center of the water.
- Turn on the stove to bring the water to a boil.
LAB SAFETY: Use caution when handling boilingwater. Monitor the apparatus at all times and never handle a hotpan without a hot pad or oven mitt. - Once the water begins to boil, wait one minute and record thetemperature on the thermometer in Table 3.
- Wait five minutes and observe another reading of thethermometer. Record the temperature in Table 3.
Table 3: Temperature of Boiling Water over Time
Time (min.) | Boiling Temperature (°C) |
1 | |
5 |
Post-Lab Questions
1. Describe what happened to the temperature of the water as itwas melting.
2. Hypothesize how the temperature of the water changed as itwas freezing.
3. What happened to the temperature of the water after itmelted?
4. What happened to the temperature of the water as it washeating?
5.What happened to the temperature of the water after it startedboiling?
6.What was the temperature of your boiling water? The standardboiling temperature for water is 100 °C. Does your measurementagree with this? Explain why or why not.
7.Explain why temperature does not change during a phase change.Where does the heat energy go if not into increasing or decreasingtemperature?