A few problems

Here are the problems we did in class today.  I will put a few more on here for Monday.  Use Coulomb's Law.

1.  A balloon rubbed against denim gains a charge of -8.0 μC.  What is the electric force between the balloon and the denim when the 2 are separated by 5.0 cm?

2.Two charges of +60.0 μC and +50.0 μC exert a repulsive force on each other of 175 N.  What is the distance between the two charges?

3.Two identical conducting spheres are placed with their centers 0.30 m apart.  One has a charge of 12 x 10-9C and the other has a charge of -18 x 10-9C.  A)  Find the electric force exerted on one sphere by the other.   B)  If the two spheres are connected by a conducting wire, after the charges have rearranged, find the electric force between the two spheres.

4.  Calculate the net electric force on each charge if the charges 
           are +3.0  μC, +4.0 μC, and -2.0 μC and the positions are at 0.0 cm, 3.0 cm, and 7.0 cm.

5.  Calculate the net electric force on each charge if the charges are -4.5 μC, +7.5 μC, and -6.0 μC.

6.  Draw the electric field lines around 2 point charges:  +2 and -3.

7.  Draw the electric field lines between two charged plates.  Show the direction a test charge (positive) would move in the field.

Nuclear Physics Review

1. a) How many protons and neutrons does Re-186 have? b)  List 2 other possible isotopes of it.

2.  How do nuclei hold together?  What are the 2 forces?  What role do neutrons have in holding nuclei together?

3.  Would the following isotopes be stable?  H-1, Ta-150, In-115, O-15?

4.  Calculate the binding energy of the following isotopes:   a)  N (14)   Atomic mass=14.003074    b)  Xe-131  Atomic Mass = 130.095069

5.  Write the alpha decay of  Th-232

6.  Write the beta decay (electron) of B-12 and the beta decay (positron) of Pb-208

5/14-5/25

Extra Credit Lecture at the Arlene Schnitzer Hall on Thursday 5/17 at 7:00 pm.  John Cacioppo will talk about "Human Nature's Social Brain."  On Monday, June 4th, our last SPARK lecture will feature Lincoln's own Ms. Wadkins talking about Binary Eclipsing Stars.

• Mon 5/14:  Do planning/research for Astronomy Projects.  Short nuclear physics quiz on Friday.

• Wed 5/16:  2 Astronomy Presentations.  Review nuclear physics.
•  
• Fri 5/18:  Nuclear Physics Quiz.  2 Astronomy Presentations.
•  
• Tues 5/22:  3 Astronomy Presentations.
•  
• Thurs 5/24:  2 Astronomy Presentations.  Astronomy Test based on all of the presentations.  Test will include 9 multiple choice questions and you will choose 5 out of 9 short answers.  (You may use notes that you took during the presentation, but that is all).

4/30/12-5/11/12

• Mon 4/30:  Questions on review?  Turn in 14+15 Review.  Take 14+15 Review.  When done, start Nuclear Physics (Chapter 25). 
• Wed 5/2:  More on Nuclear Physics:  nuclear stability and binding energy.  Binding energy problems.  Start working on Astronomy Project.
• Fri 5/4:  Check off binding energy problems.  Nuclear decay and half-life.  Work on problems.  Group time on projects.
• Tues 5/8:  Check off problems.  Nuclear fission and nuclear fusion.  Fundamental forces and classification of particles.  Prepare for Libary Research on Thursday.
• Thur 5/10:  Library Research for Astronomy Project.  This is our main day for research, so get as much done as possible.  By the end of the period, you will hopefully have your resources selected and citations written down, a summary of what you want to cover, and a strong idea of your visual aide.  We will begin presenting next week on Wednesday 5/16.

14+15 Test on Monday 4/30!

Come in on Monday prepared to ask questions and take the test.  The 14+15 Review sheet is due before the test as usual.  Here are numeric answers for the test:

1.  f = 28 cm,  M = -.48, small, real, inverted
2.  q = 11.3 cm (use substitution to get rid of one of the variables, p or q)

3.  concave mirror, M = - 20.0, larger, real, inverted
4.  q = 170 cm, M = -2.7, h' = 22 cm
5.  f = 200. cm, M = 1.25, larger, upright, virtual
6.  23 degrees

7.  critical angle is 37 degrees, so refracted

(p.s. For students in 4th period, the answer to #20 on the 14+15 problems is 48 cm.  We will go over this on Monday 4/30).

Make sure that you know how to use ray diagrams to locate an image.  You will be required to do one, although you can choose a lens problem or a mirror problem.  Make sure that you can show the refraction of light through a substance.

Enjoy your week-end and start thinking about that Astronomy Project!!

Beginning of 4th Quarter

• Mon 4/16:  Hand-out 4th Quarter "Deal".  Review ray diagrams.  Notes on Colors and Snell's Law.  Work on Problems 1-11 on Chapters 14+15 Worksheet.
• Wed 4/18:  Check off problems 1-11 and go over.  Take data for Snell's Law Lab.
• Fri 4/20:  Critical Angle problems and Lenses.  Work on problems 12-20 on worksheet, due Tuesday.  Go to library and make graph for Snell's Law Lab.  Lab due on Tuesday (should include neat and well-labeled data table, graph, calculations (percent error for water), and conclusion.
• Tues 4/24:  Hand in Snell's Law Lab.  Check off problems 12-20 (21 extra credit) and go over.  Hand-out 14+15 Review.
• Thurs 4/26:  Go over 14+15 Review.  Introduce Astronomy Project.  14+15 Test on Monday 4/30.

Late Work/Extra Credit Deadline tomorrow (4/9) by 3:30 pm! Musical Instruments Too!

I have just finished entering the grades for your Spring Inquiry Labs and your 12+13 Tests.  The only remaining assignment for the Quarter is the Musical Instrument Project.  I can't wait to see what you bring in tomorrow!  Don't let some of the amazing instruments from last week discourage you.  Those were some of the best instruments I have seen in 10 years of doing this project.  And remember that the write-up is just as important as the actual instrument.  Check your grade on Edbox and see if you have any questions.