Title: Penny Lab Lab Partner: Valorie Smith Purpose/Problem/Objective: Find the number of Pennies in a sealed envelope by two different experiments. Background Information: Pennies pre 1982 weigh 3.1 grams. Pennies post 1982 weigh 2.5 grams. Average of one penny is 2.8 grams. Diagram/Sketch/Image of lab set up: Materials and Methods: Envelope with pennies, envelope without pennies, pennies, balance scale, and a metric ruler. Method 1: Find the mass of one penny by plotting points from given measurements (x,y), x being the number of pennies and y being the combined mass of x. Once these points are plotted, we find the slope, which represents the mass of one penny. We then measured the mass of envelope number 38598. Using these two masses, we divided the penny by the envelope to get the amount of pennies. Method 2: We measured the diameter of one penny (2 cm) see figure one. Then we lined all the pennies up in the envelope and measure (see figure two). Then divide the measurement of the pennies in the envelope by one penny to get the number of pennies in the envelope. Data/Observations:

Mass (g)

Mass of empty envelope (g)

Mass of envelope 38598 (g)

12.75 25.85 39.70 53.60 70.10

# of pennies

5 10 15 20 26

5.60 g 19.70 grams

Calculations: L and S Questions: L1: Yes, our percent error was reasonable because it was below 5 percent, which means it was very close to the actual answer. L2: If we were to extrapolate 100 pennies in our lab, our percent error would most likely be less accurate because there are larger numbers which gives you a higher chance of coming up with an inaccurate measurement. L3: An error that could exist concerning the mass of the coins is that there could be dirt on them, impacting that weight. Also, pennies prior to 1982 weighed more than pennies after 1982. This would mean that not all of the pennies would weigh the same amount. L4: yes, my data shows the uniform mass of the pennies because we found one single mass that we determined was the mass of one penny, and based on the percent error, our measurement was close to the original measurement of a penny. L5: yes, you could use the mass of one penny to find the mass of multiple pennies. This would be a more efficient way to figure this out because it would be faster then trying to configure many other measurements when all you have to do is multiply the mass of a single penny by number of pennies that you're trying to find the mass of. S1: look at L1 S2: Yes, our data supported the purpose of finding the mass of a single penny because we did just that. Our data reveals

Diameter of one penny= 2 cm Width of pennies in envelope 38598= 10 cm

that we found the mass of one single penny. S3: look at L3 S4: Further experiments could be preformed to clarify our data. An example would be to measure the width of each penny and then divide it by the width of the pennies in the envelope. S5: The hypothesis of "if the width of a certain amount of pennies is x, then the width of one penny will be y" can

explore similar lab objectives. Conclusion: We decided that if a single penny weighs 2.5 grams, then you can determine the amount of any number of hidden pennies by weighing them and dividing the number by a single penny. We measured the mass of one penny, as I stated above. We also measured the weight of one envelope. Then we measured the envelope with a mystery amount of pennies in it. We measured and got all of our numbers by using a balance scale. The data we acquired compared to the known data in that it was a 5 percent error. I found out that what I was testing was very close to the already existing known data. My data follows a linear relationship because every time the x axis number got bigger, the y would increase as well. A limitation onto is experiment is that there were fake decals in the envelopes, and this would effect the weight of the envelope, therefore effecting what the outcome of the experiment would be. Another limitation is the fact that pennies pre 1982 weigh more then pennies after 1982, so thus would effect the outcome of the experiment as we'll by not giving you a clear answer on how much one penny weighs. To make this experiment more precise, we could have made sure that all if the pennies were from the same year with no dirt on them. This would alter the experiment because it would have taken more of an effort and we would soon realize that not all pennies weigh the same amount based in their circumstances. A new hypothesis that could test this same concept would be if a certain amount of pennies are a certain length, you can divide by that number and find the length of one penny, or basically use the length to find how many pennies are in the envelope.