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.
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• Fri 5/18:  Nuclear Physics Quiz.  2 Astronomy Presentations.
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• Tues 5/22:  3 Astronomy Presentations.
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• 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).