When a glass rod is rubbed with silk, it becomes positive and the silk becomes negative, yet both attract dust. Is it possible the dust has a third type of charge that is attracted to both positive and negative? Explain. Which model: 2 types or 3 types of charge would be a simpler model?

6. Which of the following are steps toward measuring the distance to stars using spectroscopic parallax? a) Measure the star’s spectral type and calculate the mass. b) Measure the star’s spectal type and the apparent brightness, i.e., the flux. c) Measure the star’s rotation period and the number of starspots. d) Measure the star’s orbital period if it is in a binary and use that to estimate the spectral types of both stars. e) Measure the slight wobble in the star’s motion caused by planets orbiting the star.

What single piece of information revolutionized our understanding of “spiral nebulae”, such as the spiral nebula in Andromeda, to show that they are spiral galaxies full of stars? a) We measured their average temperature. b) We placed them on the Hertzsprung-Russel diagram. c) We measured their distance. d) We measured their parallax. e) We measured their orbital periods

2. Which statement about our Galaxy, the Milky Way, is true? a) The halo contains no O and B stars while the disk contains stars of all spectral types. b) The halo contains only young stars while the disk contains stars of all ages. c) The halo contains hundreds or perhaps thousands of “super-massive” black holes. d) Our Sun is located a few light years from the center of our Galaxy. e) The Milky Way is unique in having no smaller galaxies orbiting around it.

A thin wall cubic container is half-filled with water. What is the vertical position of the center of gravity if the container is tipped over just to the point where is about to spill water? Consider the side of the cube d = 0.30 m.

a. y_CG = 0.14 m

b. y_CG = 0.21 m

c. y_CG = 0.23 m

d. y_CG = 0.25 m

Cosmic microwave background

Q: How is the CMB cosmic? Microwave? Background? Radiation?

Q: What are observed CMB properties?

Q: What is the last scattering surface?

Q: How does CMB verify the Cosmological Principle?

Q: What are the three possibilities for the cosmic geometry? How does CMB tell us about the geometry of the universe?

The New England Merchants Bank Building in Boston is 152 mm high. On windy days it sways with a frequency of 0.19 HzHz , and the acceleration of the top of the building can reach 1.5 %% of the free-fall acceleration, enough to cause discomfort for occupants.

What is the total distance, side to side, that the top of the building moves during such an oscillation?

List 4 things we can learn about a star using spectroscopy.

Suppose you have 2.0mol of O2 gas.

How many coulombs of positive charge are contained in this gas in the atomic nuclei?

Express your answer using two significant figures

Objects that move in a straight line with a constant speed—not speeding up or slowing down—have zero acceleration. We call this kind of motion: Uniform Motion. We can identify uniform motion when the object travels equal distance intervals in equal times.

We can identify non-uniform motion, or accelerated motion, when the object travels equal distance intervals in unequal times. Finally, we have two types of non-uniform motion: motion with constant acceleration and motion with a non-constant (or changing) acceleration.

Activity 1

Today you will analyze the motion of a cart traveling along an inclined track. You will begin by doing a thought experiment, predicting the motion of your object. Discuss your ideas among your group…it is okay to disagree!

Sketch an acceleration-versus-time graph for an object, starting with some initial speed, traveling on a flat track. Remember, this sketch is a prediction; what do you think it would look like? Then sketch a velocity-versus-time graph for the same case.

1. Explain the shape of your acceleration graph.

2. Explain the shape of your velocity graph

Sketch an acceleration-versus-time graph and a velocity-versus-time graph for an object, starting with some initial speed, traveling down an inclined track.

3. Explain the shape of your acceleration graph.

4. Explain the shape of your velocity graph

Activity 2

Now, using a track, cart meter stick and stopwatches, you will make some measurements to determine if a cart traveling down a ramp follows uniform or non-uniform motion.

First, mark a start point and end point on your track that is at least 1.5m long.

5. How many time/distance data points, between start and end, will be necessary to determine whether the cart is traveling with uniform or non-uniform motion? Explain your choice. Note: you may want to look at Questions 8 & 9 to help inform your choice.

6. Now, outline your measurement plan (procedure) to make this determination of uniform or non-uniform motion. You procedure should include clear instructions, such that anyone could reproduce you experiment exactly.

7. Create a data table and record your data in the space below.

8. Now you will need to use your data to calculate velocities and accelerations. Recall that we have discussed average velocity as vavg = Δx/Δt as well as vavg = (vi + vf)/2. We also discussed average acceleration as aavg = Δv/Δt. Using these equations, calculate the instantaneous velocity of your cart at each distance/time data point and the average acceleration between each pair of distance/time data points. When you have completed your calculations, organize your results into a table with four columns: time, position, velocity, and average acceleration.

9. Now you will graph your results. Plotting [1] a graph of position (y-axis) vs. time (x-axis); [2] a graph of velocity (y-axis) vs. time (x-axis); and [3] a graph of acceleration (y-axis) vs. time (x-axis). Be sure to fully label your graphs. This may be done on a computer or on graph paper. Attach your graphs to the back of this packet.

10. Based on your data and results, answer the lab questions: does a cart traveling down a ramp follow uniform or non-uniform motion? If it follows non-uniform motion, is the acceleration constant or non-constant? Support your answer with evidence from your experiment.

11. Are you confident in your answer to question 10? Explain why or why not.

12. Now, compare your answer (and resulting graphs) to the prediction sketches you made in Activity 1. Do your predictions match your results? If not, which do you believe (prediction or results) and why?

13. Finally, take some time to evaluate your procedure. Do you think it was an effective procedure? Were there any problems with it? How would you change/improve upon the procedure if you were to repeat this experiment?

Give a brief description of chaos. What features must a Hamiltonian system have in order to exhibit chaotic dynamics?

Parametric Equations Project (Launch Angle)

A 90mph fastball can leave a player’s bat at the speed of 110mph. Suppose a
batter hits such as fast ball at a height of three feet above the ground to dead
center field where the distance of the 12 foot high outfield fence is 410 feet
from home plate. The “launch angle” is the vertical angle at which a ball leaves
a player’s bat after being hit.
Assuming the only force acting on the ball is gravity (−?? ??/?
?
), determine
whether the batter hit a home run if the launch angle is ??°. Round all
calculations to three decimal places.

Submission: You will be graded on both your math and writing skills.
Therefore, all your written responses should be given in complete sentences, and
all mathematical expressions should be well-defined and include proper notation.
MS Word provides an equation feature under “Insert” which will allow you to
format the mathematical expressions.
Your submission must include the title of the project and underneath it your name.
The project will have three sections that must be titled “Approach”, “Solution”
and “Reflections”. The format and grading of these sections is as follows.
Approach: (5 points)
Write two or three paragraphs describing your approach to solving this problem.
This should include the steps you will take as well as how you will determine
whether your solution is reasonable.
Solution: (30 points)
In this section, you will provide your mathematical solution to the problem. Each
mathematical expression you provide as part of your solution must be described
or explained in writing. The manner in which your textbook presents solutions to
word problems is a good model for this section. Be sure to provide a sufficient
number of steps in detailing your solution. The textbook often skips step in order
to limit page count; you are not under such a restriction; so don’t skip steps. It
will count against you.
Reflections: (5 points)
Write a paragraph or two reflecting on this assignment. What did you learn from
the assignment? Were there any calculations that were surprising to you? What
changes might make the project more realistic?

In a schoolyard fight 75-lb Isaac shoves 90-lb Galileo to the ground. Who exerts a larger force on the other and why?

Explain the concept of Interference of Light Waves for double slit problems to a grade 12 classmate who was absent from class. Use visual aids and examples.

Select the correct answer or answers for each and explain:

1. When you take a book from your desk and put it up on a shelf above you the work done on the book depends on: (1) how fast you moved the book, (ii) depends on whether you moved it straight up or along an arched path, (iii) depends on how high the shelf is, (iv) depends on the mass of the book. d. A 80-kg baseball player while running at a speed of 5 m/s slides on the ground and comes to a stop in 3 m. True statements are: (i) Since the player had a KE at the beginning and no KE at the end energy is not conserved, (ii) From this information it is possible to determine the magnitude of the frictional force that stopped the player, (iii) ) From this information it is NOT possible to determine the magnitude of the frictional force that stopped the player, (iv) The work done by the frictional force is 1000 J.

2. A 80-kg baseball player while running at a speed of 5 m/s slides on the ground and comes to a stop in 3 m.  True statements are: (i) Since the player had a KE at the beginning and no KE at the end energy is not conserved, (ii) From this information it is possible to determine the magnitude of the frictional force that stopped the player, (iii) ) From this information it is NOT possible to determine the magnitude of the frictional force that stopped the player,  (iv)  The work done by the frictional force is 1000 J.

As the winter passes, the Earth spins as usual around the Sun. On a cold February night just past midnight, a lone astronomer spots an unusual object in the starlit sky. Near the far end of the constellation of Draco, north of the star HD 91190, there appeared a faint reflective anomaly. After careful observation over the next few hours, the astronomer noticed that the object was very close to Earth. Jotting down the coordinates and times, the astronomer came up with spherical coordinates

Feb 28^th -> (x,y,z) = (1.16 x 10⁸ km, 6.05 x 10⁸ km , 38.54 x 10⁸ km )

After many days of careful observation, the astronomer found that the object was indeed moving! By the middle of May, the astronomer was observing the object at:

May 15^th -> (x,y,z) = (1.05 x 10⁸ km, 5.73 x 10⁸ km , 38.28 x 10⁸ km )

Now, with this information, we must decide if this object will come close enough to Earth that it could collide. There are some other equations that are needed, in particular, the orbit of Earth:

r = 1.52 x 10⁸ / (1 + 0.0167 * cos(θ)) km

where θ is in degrees, found from Earth's rotation around the Sun. Thus, 0⁰ is Dec 21^st, the Winter Solstice, and 180⁰ is June 21^st, the Summer Solstice.

Find a set of parametric equations, using the Earth's position as the origin for each of the object's observations (it will change for each date).

Given this information, and assuming near-linear travel for the unknown object

1. How fast is the object moving?

2. In what direction is the object moving?

3. All of the planets in the Solar System are moving in on a nearly flat plane. How long until this object enters into that plane?

4. Does it seem like this object will hit Earth? Why or why not?

Solar energy is an alternative to fossil fuels for providing electrical power for both homes and businesses. It may be locally produced and used at the same location as the panels, which reduces distribution costs. Large facilities may be located in available space and the power added to the "grid" that distributes electricity. Solar power may be a better choice in rural or undeveloped areas where the grid infrastructure is unreliable or just not there, and it has been discussed as an alternative for reconstruction in storm-damaged Puerto Rico. It is also useful in less sunny areas, and here in Kentucky the regional power provider is developing a shared solar energy farm to supplement its conventional power plants. Even the Coal Museum in eastern Kentucky has solar panels to provide building power.

1. The Sun provides approximately 1.4 kilowatts (kW) of energy adding all the light striking one square meter perpendicular to a line to the Sun above the Earth's atmosphere. If solar panels are 25% efficient in converting this optical energy to electrical energy, and if they are oriented to make maximum use of incident sunlight, how much panel area is needed to develop 10% of the regional power production which is 3.5 gigawatts (GW) while the Sun shines? (3.5 GW is 3,500 MW. Currently LG&E has a 10 MW solar farm covering 50 acres.)

2. A typical single solar panel that would be installed on a home uses crystalline silicon as the material that creates the current, measures 1x2 meters, and produces 340 watts at 48 volts. It is said to be 17% efficient, allowing that not all the sunlight at the top of the atmosphere reaches the surface, and that some wavelengths are beyond the range over which silicon responds. How many of these panels would be needed to supply 15 kW that would fulfill the peak needs of a typical home? What area of the roof would they cover? This is for peak use, but typically the average power needs are about 5 kW.

3. If it is sunny 8 hours a day, then you would need 3X as many panels and a way to store energy to use them 24/7, but storage also allows you have fewer panels to meet peak needs. Allowing that the panels gather enough energy during 8 hours to provide power for that time and for 16 more hours, how much energy has to be stored? Consider two alternatives: pumped water and Tesla batteries. If you could pump water to a height of 20 meters, say to a pond or pool up the hill from your home, how much water by volume would have to be moved to store this energy . (Use the potential energy of gravity, mgh, to figure this out. ) For batteries, consider the Tesla "Powerwall", a module that stores 13.5 kWh of energy and provides 7 kW peak AC power.

4. Given what you know about the physics of solar, comment on the viability of it as a sole source of power for your home, and your rechargeable electric car. If you have a clever way of storing energy, mention it here too.