for students in physics and other classes at pths
The final exam for Academy Physics and Academic Physics takes place Friday 6/12 afternoon according to the schedules that are posted at the high school.
The attached practice questions and review guide will be helpful to your preparation.
Attachment: Final Exam Review online 2009.pdf
Make a new post in your blog and address the following questions. You can use what you learned from watching the video in class, or research the question on the web.
1. Why is there a debate about whether or not Pluto is a planet?
2. How is Pluto similar to the major planets? How is it different? (Describe two each)
3. What do you think of the controversy about whether or not Pluto is a planet? How should we decide who is correct?
If you post a full response before Friday at 7am you may skip the following question if you wish:
4. What is the name of the region in the outer solar system, beyond Pluto, which contains many recently-discovered large objects?
The test on our electrostatics unit will be given in class on Wednesday 3 June. The following document summarizes the facts we have learned during this unit:
Download: ES Summary.pdf
The exact questions that will be on the test are given to you in advance:
Download: CD ES Test Prep.pdf
You may prepare however you like but you may NOT bring notes to class on exam day. Calculators will be provided.
Make a new post on your blog titled "Journal 5/29" and address the following questions:
Remember Coulomb’s law, which gives the force between two charged objects separated by distance r.
Consider a system that contains three small charged objects A, B, and C. One of your classmates is making the following calculations of the electric forces they exert on each other:
1. What are the charges on objects A, B, and C in microcoulombs? How do you know?
2. If all three objects are positioned along the same straight line with object B in the middle, calculate the force of A on C and express it in Newtons. Explain how you were able to figure this out. (You will probably need to sketch the situation first, although you are not required to post the sketch on your blog.)
3. Refer to the definition of electric potential energy from last week’s journal assignment. What is the total amount of electric potential energy in this system of three charged objects? (Hint: there are three pairs of objects).
If you submit a full response before 7am on Friday morning, you may skip the next question if you wish:
4. If the mass of object B is 0.01 kg, what is its acceleration at the moment described above? Explain how you determined this answer.
Updated: if you want, you can refer to the definition of electrical potential energy from your lesson materials. It might help you address the question, even though calculation is not required here.
Electric potential energy Uq of two charged particles: The electrical potential energy of two particles with electric charge q1 and q2 separated by a distance r is:
k = 9.0 x 109 J•m/C2 and we assume that the objects are much smaller than their separation r (i.e. point particles).
Electrical potential energy is measured in units of joules. The relationship above can be used for both positively and negatively charged objects; the signs of the charged particles must be included. Notice that electrical potential energy is proportional to 1/r and not to 1/r2 as in Coulomb’s force law. The reference energy for electric potential energy is zero when the particles are infinitely far apart.
Make a new post on your blog titled "Journal 5/22" and address the following questions:
1. Explain what happens to the electrical potential energy in a system of two identically charged objects held at a distance d when they are released.
2. Explain what happens to the electrical potential energy in a system of two oppositely charged objects held at a distance d when they are released.
3. Consider the work-energy bar chart below which describes a system of two charged objects. Describe an initial and a final state that could match the chart. What can you say about the charges on the two objects, can you tell if they are the same or opposite?
If you submit a full response before 7am on Friday morning, you may skip the next question if you wish:
4. Two objects of opposite charge attract each other at a distance d. An external object pulls them further apart from each other to distance 2d. Did the external object do positive or negative work on the system of two charged objects? Explain how you know
Remember Columb’s formula for the electric force between two small charged objects:
The figure below shows six objects of identical mass and their charge as multiples of some positive charge q:
1. Rich says that the force of A on B is less than the force of C on D. Explain why you agree or disagree. If you disagree, explain to Rich what he needs to understand in order to reach the correct conclusion.
2. Amy says that the force of E on F is less than the force of C on D because the result of the formula is negative for E and F. Explain why you agree or disagree with Amy. If you disagree, explain to Amy what he she to understand in order to reach the correct conclusion.
If you submit your work on time, before 7am Friday morning 5/15, you don’t have to answer the following question:
3. Tiff says that object E will experience a greater acceleration than object F because it has a greater amount of charge. Explain why you agree or disagree. If you disagree, explain to Tiff what she needs to understand in order to reach the correct conclusion.
Make a new post on your blog titled "Journal 5/8" and address the following question:
In the early part of the 20th century, the most popular idea about the structure of an individual atom was based on the work of J.J. Thomson. In this "plum pudding" idea, the negative electrons were distributed throughout a squishy soup of positively charged substance.
Figure 1: the "plum pudding" model of the atom.
Question 1. Why does this model of the atom make sense knowing what we do about the behavior of oppositely charged objects?
In 1909 a team of scientists at Cambridge devised an experiment to test this idea. They had the technology to fire "alpha particles" at high speeds toward a sample of gold atoms and detect where the alpha particles went. Alpha particles are much smaller than gold atoms.
Question 2: What prediction does the "plum pudding" model make about the result of this experiment?
Question 3: Do some web research and find out what happened in Rutherford’s experiment. Describe what happened in your own words.
Question 4: The result of Rutherford’s gold foil experiment answered some questions, and created some new ones. Describe two of the questions that scientists had AFTER they learned the results of Rutherford’s experiment.
Make a new post on your blog titled "Journal 5/1" and address the following questions:
You rub a plastic tube with felt and thereby transfer 15 electrons from the felt to the tube.
a. Optional: Draw sketches that show the net charge on the tube and felt before and after rubbing them together. Attached the sketch to your blog post. See blogger.com help if necessary.
b. Write a math statement that describes the charge transfer for the felt.
c. Write a math statement that describes the charge transfer for the tube.
d. Explain why the felt and the tube are attracted to each other after having been rubbed together, even though the objects were not charged before they were rubbed together. This explanation should be based on your answers to b and c above. Make sure you use the terms charged, neutral, transfer and net charge correctly.
Attachment: You may find today’s summary document helpful.
Make a new post on your blog titled "Journal 4/24" and write a few short paragraphs:
“If we looked at the water inside a cup and at the air inside an empty cup with special glasses that allowed us to see deep inside things, what would we see?” Support your answer with evidence and reasoning based on our class activities.
1. Observe what happens to the wet paper and describe your observations in simple terms.
2. What do you need to assume about the make-up of alcohol to explain the gradual disappearance of alcohol from the paper?
3. Think of possible mechanisms for the alcohol’s disappearance (definition of mechanism: the structure or arrangement of parts of natural phenomena working together to produce an observed effect). Suggest at least three different mechanisms.
There are many possible mechanisms to explain what happened to the alcohol. Here are some of the ones that came up in class:
Select the four that you think are most plausible. The idea should also be something you can test with an experiment – otherwise we are not science-ing.
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