Millikan received the 1923 Nobel Prize in Physics for the oil drop experiment that was completed in 1910 about 100 years ago when knowledge of the atomic structure was not clear.

(a) what were the two main conclusions of the experiment that were worthy of a Nobel Prize?

(b) It has been reported that Millikan “cherry-picked” his experimental data. What are your thoughts on his treatment of the data – did he commit scientific misconduct?

(c) Why was oil used in these experiments?

(d) Why was it necessary to determine the terminal velocity of an oil drop?

(e) Assume a spherical drop of oil has r_o=824 kg/m³ ; the air has r_a=1.293 kg/m³ ; h=1.81x10^-5

1. What do you feel is the largest source of experimental error in your determination of R?

2. What would be the effect (increase, decrease, or no change) on the calculated value of R of each of the following experimental errors? a. The liquid level in the eudiometer tube is lower than that in the beaker, but this is not taken into consideration in the calculations.

b. The balance used to weigh the magnesium gives a mass that is higher than actual.

c. Some H2 escapes into the beaker during the reaction.

3. Most top-loading balances used in this experiment measure a mass only to the nearest mg ±0.001g. This significantly affects the calculation of R in this experiment. Explain why this is so. How might the procedure be modified to compensate for this systematic error?

Scientific Method

On a walk down to the beach, you observed that the plants change as you get closer to the sea and finally no plants grow when you get to the beach itself. You also observed that there are salt crystals in the soil close to the beach, but not farther away from it.

1.      Formulate a valid question based on the observations listed above.

2.      State a proper scientific hypothesis based on your observations and the question you asked above.

3.      How are you going to test your hypothesis?

4.      What would be the control in your experiment?

5.      What are the variables in your experiment?

The independent variable:

The dependent variable:

6.      What do you think your conclusion would be?

I am currently studying experimental analytical assays such as:

1. deletion analysis + reporter assay
2. linker scanning mutation assay
3. DNase I foot-printing assay
4. Electrophoretic mobility shift assay
5. ChIp-Seq

And I would like to look further into the applications of these methods. I am particularly comfortable with (1), (3), and (4) so any suggestions on an experiment I could test would be much appreciated. Not looking to do anything too complex but just something interesting and simple. I know that this isn't the typical homework question, but we do have to write about a paper about such an experiment that uses one of these methods.

Four factors, each with two levels were studied in a study of the performance of a process: time (A), humidity (B), pressure (C) and the temperature (D). One replicate was run a design 2⁴ and response is presented in the following table.

For this experiment use standard levels for each factor (1,2).

Use MINITAB to set up and analyze the experiment up to 2-level interactions. (i.e. AB, BC, etc…) Note: the response is in not randomized runs. Explain the results!

• What factors and interactions are significant?
• What are the p-value of interactions A*C, A*D and C*D?

2) Additional experiments confirmed that the difference in sequence between the expected genomic sequence and the experimentally determined cDNA sequence is neither due to a replication error nor to a DNA sequencing mistake. One of your coworkers decided to perform 5 independent experiments. In each experiment, the gene was first transcribed and then the transcript was purified and reverse- transcribed to produce double stranded cDNA copies of the gene. Finally, one copy of synthesized cDNA from each independent experiment was sequenced (5 samples sequenced in total). The difference between the cDNA and genomic DNA sequences described in part 1 was found in the 5 sequences. Explain why this result suggested that a transcription error was unlikely responsible for the sequence difference.

When we toss a penny, experience shows that the probability (longterm proportion) of a head is close to 1-in-2. Suppose now that we toss the penny repeatedly until we get a head. What is the probability that the first head comes up in an odd number of tosses (one, three, five, and so on)? To find out, repeat this experiment 50 times, and keep a record of the number of tosses needed to get a head on each of your 50 trials.

(a)

From your experiment, estimate the probability of a head on the first toss. What value should we expect this probability to have?

b)

Use the expected value to estimate the probability that the first head appears on an odd-numbered toss.

A researcher plans to do an experiment in the college setting concerning the effects of class size on attendance in a first year law course. He has four levels of size, namely, 15, 25, 40, and 60 students. Four colleges are involved in the study, each having eight first-year law classes, two of each class size. The researcher can assign students at random to a class within a college. All professors teach four classes; the dependent variable is grades measured after one semester. Discuss the problems of control in this situation. Consider possible uncontrolled variables and variables that are or might be controlled. Is there a possibility of confounding variables in this research situation? State one or more hypotheses for this experiment.

In a physics lab students are conducting an experiment to learn about the heat capacity of different materials. The first group is instructed to add 1.5-g copper pellets at a temperature of 92°C to 235 g of water at 16°C. A second group is given the same number of 1.5-g pellets as the first group, but these are now aluminum pellets. Assume that no heat is lost to or gained from the surroundings for either group.

(a) If the final equilibrium temperature of the copper pellets and water is 23°C, how many whole pellets did the first group use in the experiment? The specific heat of copper is 0.0924 kcal/(kg · °C).

(b) What is the equilibrium temperature of the aluminum and water mixture for the second group?

Charis conducted an experiment to study the pressure-volume-temperature (PVT) relationship in van der Waals equation of state of an unknown gas W. The experimental results were recorded in Table 3.1. Table 3.1: PVT relationship of gas W Temperature (˚C) Pressure (atm) Molar volume (ft3/lb-mole) 0 20.12 8 30 13.38 25 (a) Prove that the value of constant a = 2158.86 atm. (ft3/lb-mole)2 and determine the value of b (in ft3/lb-mole) using all the data in Table 3.1. (b) If the critical pressure, Pc of the gas is 45 atm, determine the best possible gas W in the experiment based on Table B.1 in the text book.