منتدى لغة الروح

منتدى لغة الروح (http://www.logatelro7.com/vb/index.php)
-   الفيزياء العامة (http://www.logatelro7.com/vb/f2.html)
-   -   101 حقيقة في الفيزياء (http://www.logatelro7.com/vb/t933.html)

عـــــذاري 11-14-2016 10:00 PM

101 حقيقة في الفيزياء
 


اقرأ هذه الحقائق البسيطة في الفيزياء ، استخلص منها المصطلحات ، تأكد أنك تفهمها جيد ، دائما سيتم سؤالك عنها في الفيزياء !
Mechanics

1- Weight (force of gravity) decreases as you move away from the earth by distance squared.
2- Mass and inertia are the same thing.
3- Constant velocity and zero velocity means the net force is zero and acceleration is zero.
4- Weight (in newtons) is mass x acceleration (w = mg). Mass is not weight!
5- Velocity, displacement [s], momentum, force and acceleration are vectors.
6- Speed, distance [d], time, and energy (joules) are scalar quantities.
7- The slope of the velocity-time graph is acceleration.
8- At zero (0) degrees two vectors have a resultant equal to their sum. At 180 degrees two vectors have a resultant equal to their difference. From the difference to the sum is the total range of possible resultants.
9- Centripetal force and centripetal acceleration vectors are toward the center of the circle- while the velocity vector is tangent to the circle.
10- An unbalanced force (object not in equilibrium) must produce acceleration.
11- The slope of the distance-tine graph is velocity.
12- The equilibrant force is equal in magnitude but opposite in direction to the resultant vector.
13- Momentum is conserved in all collision systems.
14- Magnitude is a term use to state how large a vector quantity is.

[عزيزى الزائر لايمكنك مشاهده الروابط الا بعد التسجيلللتسجيل اضغط هنا]

عـــــذاري 11-14-2016 10:05 PM

Energy



15-Mechanical energy is the sum of the potential and kinetic energy.
16- Units: a = [m/sec2], F = [kg•m/sec2] (newton), work = pe= ke = [kg•m2/sec2] (joule)
17- An ev is an energy unit equal to 1.6 x 10-19 joules
18- Gravitational potential energy increases as height increases.
19- Kinetic energy changes only if velocity changes.
20- Mechanical energy (pe + ke) does not change for a free falling mass or a swinging pendulum. (when ignoring air friction)
21- The units for power are [joules/sec] or the rate of change of energy.

عـــــذاري 11-14-2016 10:09 PM

Electricity

22- A coulomb is charge, an amp is current [coulomb/sec] and a volt is potential difference [joule/coulomb].
23- Short fat cold wires make the best conductors.
24- Electrons and protons have equal amounts of charge (1.6 x 10-19 coulombs each).
25- Adding a resistor in parallel decreases the total resistance of a circuit.
26-Adding a resistor in series increases the total resistance of a circuit.
27- All resistors in series have equal current (I).
28- All resistors in parallel have equal voltage (V).
29- If two charged spheres touch each other add the charges and divide by two to find the final charge on each sphere.
30- Insulators contain no free electrons.
31- Ionized gases conduct electric current using positive ions, negative ions and electrons.
32- Electric fields all point in the direction of the force on a positive test charge.
33- Electric fields between two parallel plates are uniform in strength except at the edges.
34- Millikan determined the charge on a single electron using his famous oil-drop experiment.
35- All charge changes result from the movement of electrons not protons (an object becomes positive by losing electrons)

عـــــذاري 11-14-2016 10:11 PM

Magnetism


36- The direction of a magnetic field is defined by the direction a compass needle points.
37- Magnetic fields point from the north to the south outside the magnet and south to north inside the magnet.
38- Magnetic flux is measured in webers.
39- Left hands are for negative charges and right hands are for positive charges.
40- The first hand rule deals with the B-field around a current bearing wire, the third hand rule looks at the force on charges moving in a B-field, and the second hand rule is redundant.
41- Solenoids are stronger with more current or more wire turns or adding a soft iron core.

عـــــذاري 11-14-2016 10:15 PM

Wave Phenomena



42- Sound waves are longitudinal and mechanical.
43- Light slows down, bends toward the normal and has a shorter wavelength when it enters a higher (n) value medium.
44- All angles in wave theory problems are measured to the normal.
45- Blue light has more energy. A shorter wavelength and a higher frequency than red light (remember- ROYGBIV).
46- The electromagnetic spectrum (radio, infrared, visible. Ultraviolet x-ray and gamma) are listed lowest energy to highest.
47- A prism produces a rainbow from white light by dispersion (red bends the least because it slows the least).
48- Light wave are transverse (they can be polarized).
49- The speed of all types of electromagnetic waves is 3.0 x 108 m/sec in a vacuum.
50- The amplitude of a sound wave determines its energy.
51- Constructive interference occurs when two waves are zero (0) degrees out of phase or a whole number of wavelengths (360 degrees.) out of phase.
52- At the critical angle a wave will be refracted to 90 degrees.
53- According to the Doppler effect a wave source moving toward you will generate waves with a shorter wavelength and higher frequency.
54- Double slit diffraction works because of diffraction and interference.
55- Single slit diffraction produces a much wider central maximum than double slit.
56- Diffuse reflection occurs from dull surfaces while regular reflection occurs from mirror type surfaces.
57- As the frequency of a wave increases its energy increases and its wavelength decreases.
58- Transverse wave particles vibrate back and forth perpendicular to the wave direction.
59- Wave behavior is proven by diffraction, interference and the polarization of light.
60- Shorter waves with higher frequencies have shorter periods.
61- Radiowaves are electromagnetic and travel at the speed of light (c).
62- Monochromatic light has one frequency.
63- Coherent light waves are all in phase.

عـــــذاري 11-14-2016 10:16 PM

Geometric Optics




64- Real images are always inverted.
65- Virtual images are always upright.
66- Diverging lens (concave) produce only small virtual images.
67- Light rays bend away from the normal as they gain speed and a longer wavelength by entering a slower (n) medium {frequency remains constant}.
68- The focal length of a converging lens (convex) is shorter with a higher (n) value lens or if blue light replaces red.



عـــــذاري 11-14-2016 10:19 PM


Modern Physics




69- The particle behavior of light is proven by the photoelectric effect.
70- A photon is a particle of light {wave packet}.
71- Large objects have very short wavelengths when moving and thus can not be observed behaving as a wave. (DeBroglie Waves)
72-All electromagnetic waves originate from accelerating charged particles.
73- The frequency of a light wave determines its energy (E = hf).
74- The lowest energy state of a atom is called the ground state.
75- Increasing light frequency increases the kinetic energy of the emitted photo-electrons.
76- As the threshold frequency increase for a photo-cell (photo emissive material) the work function also increases.
77- Increasing light intensity increases the number of emitted photo-electrons but not their KE.



عـــــذاري 11-14-2016 10:21 PM


Internal Energy



78- Internal energy is the sum of temperature (ke) and phase (pe) conditions.
79- Steam and liquid water molecules at 100 degrees have equal kinetic energies.
80- Degrees Kelvin (absolute temp.) Is equal to zero (0) degrees Celsius.
81- Temperature measures the average kinetic energy of the molecules.
82- Phase changes are due to potential energy changes.
83- Internal energy always flows from an object at higher temperature to one of lower temperature.


عـــــذاري 11-14-2016 10:24 PM


Nuclear Physics




84- Alpha particles are the same as helium nuclei and have the symbol .
85- The atomic number is equal to the number of protons (2 for alpha)
86- Deuterium () is an isotope of hydrogen ()
87- The number of nucleons is equal to protons + neutrons (4 for alpha)
88- Only charged particles can be accelerated in a particle accelerator such as a cyclotron or Van Der Graaf generator.
89- Natural radiation is alpha (), beta () and gamma (high energy x-rays)
90- A loss of a beta particle results in an increase in atomic number.
91- All nuclei weigh less than their parts. This mass defect is converted into binding energy. (E=mc2)
92- Isotopes have different neutron numbers and atomic masses but the same number of protons (atomic numbers).
93- Geiger counters, photographic plates, cloud and bubble chambers are all used to detect or observe radiation.
94- Rutherford discovered the positive nucleus using his famous gold-foil experiment.
95- Fusion requires that hydrogen be combined to make helium.
96- Fission requires that a neutron causes uranium to be split into middle size atoms and produce extra neutrons.
97- Radioactive half-lives can not be changed by heat or pressure.
98-One AMU of mass is equal to 931 meV of energy (E = mc2).
99- Nuclear forces are strong and short ranged.


عـــــذاري 11-14-2016 10:24 PM

General

The most important formulas in the physics regents are:


Physics is fun. (Honest!)


الساعة الآن 03:43 AM.

Powered by vbulttin
Copyright ©2000 - 2017.


HêĽм √ 3.1 BY: ! ωαнαм ! © 2010

أن المنتدى غير مسئول عما يطرح فيه أفكار وهي تعبر عن آراء كاتبها


SEO by vBSEO 3.6.1