Honors Research, Topics in Physics

All those taking or hoping to take honors research Topics in Physics stay tuned. There will be info on the subjects and a first period section may open up.

Summer and Projects

I have taken home a large Knx project and awarded a leaf blower to the physics department. If you would like to undo either of these allocations, let me know via email immediately.

To all of you, thanks for your work, patience, good humor and interesting personalities.

All those taking or hoping to take honors research Topics in Physics stay tuned. There will be info on the subjects and a first period section may open up.

Urgent Honors Period 2 Anonymous Hwrk

I have a large mass of thermo and Fluid Homework with no name from period 2 . E mail me immediately if you are the culprit

URGENT ALL STUDENTS PIck up Projects

All projects in my room at noon Thursday become my property to keep or dispose of as I see fit.

Come get your stuff if you want it!!!

Great Adventure

Reading your labs is the great adventure. It seems that many of you entered an entirely new universe at the amusement park. If you are still working on ours, try to avoid creating a whole new regime of physics. Try doing some intelligent observation and deduction. Your mass in Kg is your pounds/2.205 something between 50 and 90 kg for most of you.  Momentum changes if speed changes and momentum is low when you go slow no matter how high you are. PE increases with height.

For example:

Most of you seem to think that when you feel a force 3 times your weight you actually feel lighter than normal. 

Some of you think your mass is about  6 kg, the equivalent of 13 lbs. Many of you think we should use pounds instead of Newtons for wieght in metric calculations. You seem to forget that your weight is mass (kg) x g    (g  is 9.8 N/kg on earth).

Some of you claim the outer and inner ring of horses on the carousel were just .3 m apart, i.e. 1 foot. It must have been pretty crowded on that ride.

Some of you think the inner horses go around more rotations than the outer ones. Neat trick

Others think the horses go up and down 65 or even 90 times per rotation  of the carousel. That would be a pretty exciting ride. A few said the ride took 3 minutes to go around once, because the period is the time to amke one cycle, not the time from the start of the ride to when it finishes

Many of you confuse momentum and energy. In fact you use the word momentum with no indication that you know what it means. To say the ride builds momentum as it rises even though it nearly stops at the top of the first hill, is to show you really don't know that momentum = mass x velocity. To say momentum is the the same throughout the ride is worse since the v is very high at the bottom.

Most of you can recognize that KE = m v^2/2 especially when it is written o every second page of the lab sheeet.  Some of you say that maxium KE and maximum speed occur at different places, even though KE is proportional to speed squared. Can maximum speed squared occur at some place where the speed is not the maximum?

Some of you think gravity was pulling you upward at the top of the loop, this is a most unusual direction for the gravitational force.

There is more, but I must go back to reading the installments in science fiction and fantasy you have prepared for my entertainment.

Honors 1 Lens Labs

The following are in jeopardy of  no credit for their lab on convex lenses:Kyle, Meaghan, Chris, Brett

 because your ray diagrams having nothing in common with correct ones. To receive credit you will have to provide correct drawings of the four cases [ do is object distance] do >2 f; do=2f; 2f>do>f; do

This is not so tough because these ray diagrams are in the notes on geometric optics you were to have downloaded and read 3 weeks ago and that you'd better be reviewing for the final.

Andrew, Mike, Dennis, Steve and Anne Marie should also do this if they want decent grades for this lab.

Sorry for being so public, but I haven't been able to connect with the Bernards mail server today

Additional Honors Review Material

Don't panic, its not much

RevShtHnrsSpring-08Add.doc

More solutions to Honors Review are to come

Let me know by email if you can't read these ALSO. There will be a little more review material on magnetics and thermo and maybe circuits so stay tuned.

Honors Review Spring –08 Solutions Prt2

IX. .1 .482 V Toward B Away from A IX.2 1.73x10¹⁰ Vthis is one reason why whole uneutralized coulombs are not found in nature. IX.3 1.92x10^-16 J. IX.4 28.3 ohms; .21 A; yes;I_B =.14 A I_C = .07 A; V_A = 3.2 V V_B=V_C=2.8 V; P_A =.68W P_B = .392 W

P_C = .196W

X. 1 B= 1.4x10^-5 T. X.2 F=1.1x10^-11 N X.3 EMFor voltage = 3532 V

Optics page 27

1. try it but don’t waste any time 2. di = 30cm Mag = 2x 3. AM radio low end of frequency spectrum gamma rays high end 4. 4.37x1014 5. 1.18x10^-14 6.Light passes through real image, light only seems to come from virtual image 7. q_incident = q _refl

8. di =27.5 cm Mi = .83 9.missing in action 10.di =26.7 cm M =1.667 11. f = 30 cm 12 do =15 cm

Refraction and more lenses Page 29

1. ni index of refraction for 1st ( incident) material nr index for 2nd (refracting ) material

qi angle incidence, qr angle of refraction. refraction: bending of light at surface between two materials as speed changes total internal reflection light bends so much away from normal it doesn’t penetrate second material i.e. qr = 90 deg happens only when nr

3. c = 1.94 x10⁸. 4.sinq water /sinq lucite = n_lucite/n_water q_water = 37 deg 5. sin 90 =1 so sinqcrit = n_air/n_water.=1/1.33 qcrit = 48 deg 5. n_gem/n_air = 1/sin 41 = 1.52 so n_obj =1.52 its glass 6. nmatl = sin 37.5/sin 25.6=1.4 7.b 8. total internal reflection and diffraction of sunlight inside water droplets ( don’t waste time on this now) 9. reflection light bounces off and is not transmitted into new medium, refraction: light bends as it enters new medium 11.C its virtual and erect 12. D bends away from normal 13. q_reflect = 45 deg, q_refraction = 32 deg 13. do = 2f so image is real inverted same size di = 2f = 20 cm

15. cglass = 2x10⁸m/s 16. c 17. A 18 still 48 deg.

AP FINAL

I just spoke with Mr. Howlett and because of the contradictions in information provided to teachers and students by different parts of the administration we have decided on the following policy. The final is now optional for all students who took the AP exam, which is all of my students.

The exam will allow you to raise your grade. It will be graded on the very liberal AP scale 39% is a C 50 % is a B 65% is an A. It will comprise 70 MC and two FR from a real AP. To prevent your taking it without studying it will count whether it raises or lowers your grade.

You must respond to ASAP so I know if I have any takers for Monday morning.

Dr. Cherdack

Honors Review Solutions Part 1

Here are solutions for the first half. Stay tuned for more solutions and more news about what you need to know

HnrSprngRev08solnspt1.PDF

SHM means Simple Harmonic Motion

SHM means Simple Harmonic Motion. That's it that's the purpose of this post

Mathematical Homework and Review Solutions

Homework: you must do 3 problems from each of the 11 groups of problems, you must show work, not copy answers or my calculations and you must choose real problems or essays, no one or two word answers. Its due Friday at the exam.

Also, BRING IN YOUR BOOK

Here are the solutions . Let me know if I have to post a link or you can read this well enough.

Mathematical Physics Final Exam Review

Solutions to Problems

Oscillations and Waves

1. 1/5 or .2 Hz 2a. .04 s 2b. T = 2pi sqrt(m/k) ; m= 2x10^-4kg 3. T =5.44 s

4. 2250 N 5. 5. 900 N 6. 3.11 m 7. 136 Hz 8. 670 nm 9.a because the wavespeed increased 10. no drawings here come see me if you need to 11. c = srqt ( F_T/(M/L)) = 44.7 m/s first harmoci l = 2l = 4m F 44.7/4 = 11.2 Hz 12. c 13. b 14. a 15. b 16. b

17. 1 s ; 1Hz; new period =1.41 s 18. Waves in phase amplitudes add, produces maxima in light or sound or whatever type of wave 19. b 20a 21 k is spring constant in N/m; x is distance from equilibrium point 22.more

More Waves page 8

1. 1.3m 2. 30C 3. 103,000 Hz 4.no for both 5. c =256 x( 4x.33) = 338 m/s 6. 2L = c/f , L= 340/786 = .43 m 7. 6.3 Hz 8a. f = 850 (340/340-35) = 944 Hz 8b. f = 771 Hz

9. waves reflected from bottom arrive at top in phase with waves created or reflected at the top. 10. Open tube 2L =l or f =c/2L =343 Hz

More waves page 9

10. L = Nl/2 so f= c/l = Nc/2L

putting a cap on it changes it to one end closed L=Nodd l/4 or f=Nodd x c/4L

11.B 12. A 13. D 14.B 15. hot

Optics page 15

1. try it but don’t waste any time 2. di = 30cm Mag = 2x 3. AM radio low end of frequency spectrum gamma rays high end 4. 4.37x1014 5. 1.18x10^-14 6.Light passes through real image, light only seems to come from virtual image 7. q_incident = q _refl

8. di =27.5 cm Mi = .83 9.missing in action 10.di =26.7 cm M =1.667 11. f = 30 cm 12 do =15 cm

Refraction and more lenses Page 17

1. ni index of refraction for 1st ( incident) material nr index for 2nd (refracting ) material

qi angle incidence, qr angle of refraction. refraction: bending of light at surface between two materials as speed changes total internal reflection light bends so much away from normal it doesn’t penetrate second material i.e. qr = 90 deg happens only when nr

3. c = 1.94 x10⁸. 4.sinq water /sinq lucite = n_lucite/n_water q_water = 37 deg 5. sin 90 =1 so sinqcrit = n_air/n_water.=1/1.33 qcrit = 48 deg 5. n_gem/n_air = 1/sin 41 = 1.52 so n_obj =1.52 its glass 6. nmatl = sin 37.5/sin 25.6=1.4 7.b 8. total internal reflection and diffraction of sunlight inside water droplets ( don’t waste time on this now) 9. reflection light bounces off and is not transmitted into new medium, refraction: light bends as it enters new medium 11.C its virtual and erect 12. D bends away from normal 13. q_reflect = 45 deg, q_refraction = 32 deg 13. do = 2f so image is real inverted same size di = 2f = 20 cm

15. cglass = 2x10⁸m/s 16. c 17. A 18 still 48 deg.

Electrostatics Page 23 etc.

1. gained extra electrons and now repelled by extra electrons on the dome. 2. Gives electrons somewhere to escape to and can provide electrons when needed. 3. 9.6 x10⁴ C

4. .225 N away from 5. r² = q_Tkq_S/F so r = .135 N 6. E= F/q =3x10⁶

7. q = .6/24 = .025 C 8. 9.6x10^-12 9. excess electrons flow to leaves and repel each other, finger drains excess electrons 10. conduction tough rod to scope; induction hold rod near scope and allow some electrons to leave scope and go to finger. 11 Lines go from positive to negative. Lines are twice as crowded around positive charge since it has twice the charge.12. Missing info

Capacitance and Potential Page 25 Note correction last equation for DV on upper page 25 is DV =E dot d

1. Capacitance, voltage drop, charge, potential energy, distance, 9x10⁹,electric field

2. Coulombs, joules, Farad, Newton, Volt, meter, N/c or V/m. [the other]2. .101 J

3. 7.2x10^-8J 4. 10^-6;10^-9;10^-12 5.q=CV = 1.125 nCoul. 6. Cq/V =5.8 mF.

PE =QV/2=1.05x10^-4 J 7.this one is on you do it 8. 5V 9. store charge and energy ( really they pass AC and stop DC but that’s to advanced for you,) metal plates close to each other with air, plastic, or vacuum in between.

Currents and Circuits Page 29

1. electrical potential ( voltage); current; resistance; power. 2. beginning with Watts ending with farads: 10,9,7,1,5,6,8,4,2,3. 3 17 ohms 4 5V ( again) 5.d 6 b 7. 14.7 ohms, VI = 3300Watts, 9.9kWh 8. your turn 9. P =V²/R so R = V²/P = 192 ohms 10. 5kW x 12 x 92 days = 5520 ( about $800 these days) 11 ran away 12. a 13. b 14. rubber 15. copper 16. c 17. b 18. 1 ampere 19. potential energy per coulomb, volts 22 resistance to electrons flowing when voltage is across element, ohms 20.same voltage at all points on bird, no field in bird so no current 21 no effect I = V/R =2V/2R 22.( right place this time) dimmer, share the voltage each gets fewer volts. 23. a. 12V of course, b. I=12/7 amps, c. 7 ohms d. 12/7 amp – same- everywhere in series circuit. 24. pull a bulb out if others light parallel if not series. 25. b) 30 ohms c) 4V d) 1/5 amp 26. b) 6.67 ohms c) 12 V across each parallel resistor, d) 12/20 amps = .6 amps

27. R equiv = 4.4 ohms I circuit = 48/4.4 = 10.9 A

	2 ohm	4 ohm	6 ohm
I (A)	10.9	6.55	4.37	10.9
DV	21.8	26.2	26.2	48
P ( W)	238	172	114	524

28.D 29. D 30. C 3Amps 31. C 60 V 32. D 360 W 33. 2 A Total resistance is no 30 ohms total current is 4A and half passes through meter. 34 all of a,b, and c are true 35. d

36.75 watts = .075 kW .075 x 168 hrs = 12.6 kWh at $.1 per kWh costs= $1.26

37. b 38 T 39. T 40. T 41. F 42. F 43. T

Magnetism Page 34

1. A 2. 2 x10^-5 T 3. No only component perpendicular to field yields a force

4. F = 1.6x10^-19 x 3x10⁶ x 2 =2.3 x10^-12 N 5. EMF = -200* -1.6*.02/.2 =32 V

Fluids page 35

1. 90,000 N 2. 131,000 Pa 3. FB = 2.5 m3 x 1000 x10N/kg = 25000N 4. Use Bernoullis’s P₁-P₂ = 0 v₁ =0 so v2 = -2 g(h₂-h₁) = -2x10x (-3) = 60 so v₂ = 7.75 m/s

Thermo dynamics page 35

1. isothermal 2. n = 60 moles 3. 2x106 Pa 4. PDV = 5 x10⁶ J , T intitial = PV/nR =241 K, T final = 1444 K

Honors Review Revision 1

Here is I hope the last update. Get through page 16 at least tonight.

I will be here for help, etc. during my usual hours during finals week although I do hope to leave by 2:30 on finals days.

RevShtHonorsSpr-08r1.doc

Obsolete Honors Finals Review Package

SEE Tuesday Post

Here it is. Do first 12 pages by Wednesday. There may be revisions so keep checking.

RevShtHonorsSpr-08.doc

Mathematics Latest and I hope last Review Sheet

Sorry its so long, try to do about 8 sheets per night. You should be about finished with light by now. We will finish waves and light tomorrow and E and M on Wednesday. This leaves the short period  on Thursday and any time outside of class hours up to your test on Friday.

CPMSpringreview08J.doc

Mathematical Review for Physics

Here is this afternoon's update of the review sheet. Its good up to middle of page 28. Final version should be out tomorrow.

CPMSpringreview08H.doc

Honors Quiz on Fluids and Thermo

For the quiz expect to define and find pressure, find velocity for a flowing fluid, know how to calculate flow rate(m3/s), understand and use buoyancy ( Archimede's principle), understand the basics underlying thermo and gas pressure, and be able to do a simple cycle and calculate efficiency.

Thermo cycle for tomorrow: use the same diagram and same format as the table in the Thermo Notes. Here are the new values. Complete table and compute efficiency for this cycle

Point T (K) P (Pa)        V (m3)       Process     DU (J)        W by (J)             Qin (J)
A 300           3.6x107                        A-B
B 1500          3.6x107                        B-C                           2.21x109
C 1500                                900        C-D
D 300             6x105           180       D-A                          -4.42x108

Mathematical Review for Final as of Sunday 11 PM

Here is the latest version, good to page 25.  This goes from waves to light, before covering electricity and magnetism. I don't like this but it is the way the other mathematical course are taught. Electricity and Magnetism will be completed in the next version and then fluids and thermo.

CPMSpringreview08G.doc