# What is Physics 2: Definition and 74 Discussions

Physics (from Ancient Greek: φυσική (ἐπιστήμη), romanized: physikḗ (epistḗmē), lit. 'knowledge of nature', from φύσις phýsis 'nature') is the natural science that studies matter, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over much of the past two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the Scientific Revolution in the 17th century these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy.
Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism, solid-state physics, and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.

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1. ### Calculating the Electric field inside an infinite planar slab using Gauss' Law

Draw a Gaussian pill box that starts from 0 (half way between the slab) and extends towards 2 cm.$$A \times \int_{0}^{0.02} \rho dz$$ I'm not sure if I should multiply the integral by A (area) or V (volume) And if area would I multiply by 0.02^2? I'm confused here. Thanks for your help.
2. ### I with this Circular Aperature Diffraction Problem please

I know that in order for the two lights to be distinguishable from one another they have to be separated by an angle of at least theta = 1.22(wavelength)/(width of aperture). I tried drawing the given picture below and then using trig to find L in terms of d/2 and theta/2. However, this ended up...

4. ### What other information is needed to solve this equation involving b?

the equation is not equal not to anything (example: 3x = 6) and i don't know how to resolve [e ^ - (b / 2m) t].
5. ### Seemingly simple Physics 2 wave question (third harmonic frequency)

I cannot find the correct answer anywhere online and the answer I keep getting is 5.4 (incorrect) Please show me the process to get to the answer! Thank you
6. ### Studying What's the best way to apply the concepts learned in physics 2?

I'm finishing up physics 2(intro E&M) at my college, and I'd like to apply the concepts I learned in it over the summer. I was considering working through an electronics book, or building a radio, etc. What kind of projects or books do you recommend to cement some of the topics I learned in a...
7. ### Infinite number of identical charges r=a2^n

Homework Statement Homework Equations V=k∑q/r E=-dV/dsThe Attempt at a Solution I found part A plenty fine, 2kq/a From here, I thought that the derivative of -V would give me the electric field, giving -2kq/a^2, but that's not the answer according to what my professor sent. I'm wondering...
8. ### Courses Should I take Calc 3 before Physics 2?

I've heard several people mention that physics 2 uses a lot of material covered in calc 3 (multivariable I believe would be its equivalent). The physics 2 course at my college covers Coulomb's Law, electric fields and potentials, capacitance, currents and circuit, Ampere's Law, Faraday's Law...
9. ### Rank charges in spheres (Physics 2)

Homework Statement Homework Equations None (conceptual) The Attempt at a Solution My logic here is this, Sphere 3 has a net positive charge so it is repelling the positives in sphere 2 and attracting the negatives in sphere 2. This means that D has negative charge and C has positive charge...
10. ### Courses How to prepare for Calculus Based Physics 2?

hello, Some background I transfer to SUNY Albany in Fall 2017 and took the following courses Organic chemistry 1: C+ Calculus 2: B- A PHY 140 Physics I: Mechanics (3): E (like F) An introduction to the fundamentals of physics: Classical Mechanics. Topics include the concepts of force, energy...
11. ### Courses Find the Perfect Online Calc-Based Physics 2 Course with Lab for Summer"

Hi, I was wondering if anyone knew of an online calc-based physics 2 course with a lab? I know it's a lot of criteria to match and I've had a pretty hard time searching, but I thought I'd ask in case someone else has taken or is aware of something! I need to take it this summer in order to be on...
12. ### Why do Christmas lights glow green near a Tesla coil?

Homework Statement For a high school physics class, I chose to build a tesla coil for a real world application assignment. I was able to build it fairly easily and it turned out great. Before presenting to the class next week, I've been seeing its effect on different types of light bulbs and...
13. ### Electric Potential vs Electric Potential Energy

So in my physics textbook a problem is stated. We are given an external electric field directed downwards of 150N/C. We are then told that an electron is released in the electric field and it moves upwards 520m. Finally we are asked to calculate the change in electric potential energy of the...
14. ### Calculate the total force on Q1

Homework Statement Q1<------>Q2<------>Q3 In the above figure, the distance between Q1 and Q2 is equal to the distance between Q2 and Q3. That distance is R=1.5 m. Q1= 2.24x10-6 C, Q2=+Q1 and Q3=-Q1. Calculate the total force on Q1. Give your answer with a positive number for a force...
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### Pressure at the center of an accelerating sphere

Homework Statement Consider a glass sphere completely filled with water except for a small air bubble at 1 atmosphere. The sphere is accelerating to the right. What is the pressure at the center of the sphere? Let Pe = Atmospheric pressure r = radius of sphere pw = density of water a =...
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### Courses AP Physics 2 without AP Physics 1?

Hey, all! My situation is as follows: I'm an upcoming senior in high school and in the middle of my junior year I developed an interest in physics. However, at my school, AP Physics 1 is taken junior year and AP Physics 2 is taken senior year. I didn't take AP 1 because I was indifferent to...
17. ### Finding the magnitude of electric field

Homework Statement A uniform electric field exists in the region between two oppositely charged parallel plates 1.59 cmapart. A proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate in a time interval 1.50×10−6 s . Find the...
18. ### Calculating Entropy Change in a Lead-Lake System

Homework Statement A 5.0-kg piece of lead at a temperature of is 600 Celsius placed in a lake whose temperature is 15 Celsius. Determine the entropy change of (a) the lead piece, (b) the lake, and (c) the universe. mass of lead=5 kg initial temperature of lead=873.15 K final temperature of...
19. ### Courses Failed Physics 2. What can I do to help get better?

Sorry for long post, but please bear with me. I have always wanted to enter a STEM field with original intentions being computer programming. In high school I gathered a lot of interest in science and particulary physics. I aced my high school physics courses as well as my local community...
20. ### Engineering Finding the Total Force on the Circuit Loop

Homework Statement The problem asks to find the Total Force on the Circuit Loop. I have a circuit loop with length 30.0 cm and width 10.0 cm with a current I2= 30.0 A that is flowing counter-clockwise. There is a wire that has the current I1=15.0 A flowing from left to right and is 7.50 cm from...
21. ### Calculating the Potential Energy of a 3-point charge config.

Homework Statement Charge q1= 8.5 nC is located at the coordinate system origin (0,0), while charge q2= -4.46 nC is located at (a,0), where a= 1.5 m. The point P has coordinates (a,b), where b=0.95 m. A third charge q3= 16.5 nC will b added later. It is a 3 part question, first asking for the...

Homework Statement A radio broadcast antenna is located at the top of a steep tall mountain. The antenna is broadcasting 104.3 FM (in Megahertz) with a power of 5.00 kilowatts. What is the peak intensity of the signal at a receiving antenna located 25.0 km away? Homework Equations Honestly...
23. ### Concentric Coils EMF from Graph

Homework Statement Two concentric circular coils of wire lie in a plane. The larger coil has 61 turns and a radius of a = 7.40 cm. The smaller coil has 58 turns and a radius of b = 0.95 cm. The current in the larger coil has a time dependence as shown in the figure. Picture and graph...
24. ### Courses My physics 1 & 2 teacher skipped so much material....

I go to a community college for mechanical engineering and I always thought that physics 1 and 2 were way too easy and that my teacher probably skipped a lot of important material. One of my friends just transferred to a university to major in physics and he's been telling me that we didn't...
25. ### Magnetic Field in a Semi-Infinite Wire

Homework Statement Homework Equations B = μi / 4πR is the equation for a semi-infinite straight wire The Attempt at a Solution I know that for each situation in a,b, and c I would use the equation I listed above, but I am not sure what I would plug in for R for each situation.
26. ### Electric Field, Potential, and Work at a Point

Homework Statement Homework Equations E = kq/r2 V = -∫ E ⋅ ds W = -Vq The Attempt at a Solution a) I just summed up the electric fields: +ek/a2 +ek/a2 -ek/a2 so I get +ek/a2 as a result. Not sure if this is correct since -e has a y component so I was thinking to use sin but not sure which...
27. ### Finding Electric Field and Work at a Given Distance? Need help with Problem 1

Need help with Problem 1 Homework Equations E = kq/r2 V = -W/q V = kq/r The Attempt at a Solution 1a. dE = kdq/rRSUP]2[/SUP] dq = p ds dE = kpds/R2 Not sure if I am right up to this point and don't know how to proceed. 1b. I think the electric field would be zero since the enclosed charge...

29. ### General Physics 2 vs Modern Physics

I'm finishing up my general physics 2 course (today actually) and I begin my upper division courses in Fall. I was wondering how you found general physics 2 compared to intermediate modern physics in terms of difficulty? I found physics 2 (basically introductory E&M at my school) more difficult...
30. ### What is the width of a square well if its ground-state energy is 2.50 eV?

Homework Statement An electron is bound in a square well of depthU0=6E1−IDW. What is the width of the well if its ground-state energy is 2.50 eV ? Homework Equations En = h2n2/8mL2 The Attempt at a Solution I used n = 1 so I get: 25eV*1.6*10-19 = h2/8*9.11*10-31*L2 I got L = .388 nm. It...
31. ### EMF Pinewood Derby: A Practical Physics Project

I'm taking physics 2 and was told to create a practical project utilizing electromagnetic force. Starting thinking about Lenz's law (which I just read in a textbook for the first time a week ago) and I thought it would be fun to send a pinewood derby car uphill instead of down. The sprinkler...
32. ### Magnetic Field at the center of a square loop

Homework Statement A square wire loop 12.0 cm on each side carries a clockwise current of 15.0 A Find the magnitude of the magnetic field at its center due to the four 1.30 −mm wire segments at the midpoint of each side. Homework Equations B = (μ0*I)/(4π)*(2a)/(x√(x^2+a^2)) The Attempt at a...
33. ### Schools Taking College Physics 2 before Engineering Physics 2?

Hey everyone, I am trying to strategically plan my semesters ahead. This Summer I am planning on taking Engineering Physics 1 and Cal 3 (or College Physics 2 in place of Cal 3). Prior to this semester, I had no experience with Physics, so I enrolled in College Physics 1 to see how it goes. I...
34. ### Calculating Electric and Magnetic Field amplitude

Homework Statement A circular uniform laser beam has a power of P = 3.2 mW and a diameter of d = 8.5 mm. The beam is a form of electromagnetic raditation with both electric and magnetic field components. (a) Calculate the intensity of the beam in units of W/m^2 (b) Calculate the energy (delta...
35. ### Modeling a falling body

Homework Statement The speed of a falling body might be based on the observation that the velocity of a falling object seems to increase the further it has fallen. Model the hypothesis "The speed of a falling object is proportional to the distance it has fallen" as a differential equation...
36. ### Cyclotron magnetic field questions

Homework Statement Cyclotrons are widely used in nuclear medicine for producing short-lived radioactive isotopes. These cyclotrons typically accelerate H− (the hydrideion, which has one proton and two electrons) to an energy of 5MeV to 20MeV. This ion has a mass very close to that of a proton...
37. ### The Electric Potential Equation

Homework Statement An object with charge q = −4.00×10−9 C is placed in a region of uniform electric field and is released from rest at point A. After the charge has moved to point B, 0.500 m to the right, it has kinetic energy 5.00×10−7 J .What is the magnitude of the electric field? Homework...
38. ### Exploring Factors Affecting Electric Shock While Exiting a Car

Homework Statement 1)a student decides to investigate the electric shock she received when she gets out of her car. Which of the following factors least likely to have a significant effect on the size of the shock? A. The material of her clothe B. The distance she slides across the seat when...
39. ### Calculating Electric Field Using Gauss' Law for a Charged Insulating Slab

Homework Statement A slab of insulating material has thickness 2d and is oriented so that its faces are parallel to the yz-plane and given by the planes x=d and x=−d. The y- and z-dimensions of the slab are very large compared to d and may be treated as essentially infinite. Let the charge...
40. ### Refraction in Isosceles triangle [Uni Phys 2]

Homework Statement Suppose the isosceles prism of the figure(http://imgur.com/EQiQSoO) has apex angle φ = 53.4° and index of refraction n = 1.41. (a) What is the smallest angle of incidence θ for which a ray can enter the left face of the prism and exit the right face? (b) What angle of...
41. ### [Uni Physics 2] Inductance Problem

Homework Statement Two identical long wires of radius a = 2.90 mm are parallel and carry identical currents of i = 5.00 A in opposite directions. Their center-to-center separation is W = 17.0 cm. Neglect the flux within the wires but consider the flux in the region between the wires. What is...
42. ### [Physics 2 w/calc Uni] Cylinder inside of a cylindrical shell

Figure (a) shows a narrow charged solid cylinder that is coaxial with a larger charged cylindrical shell. Both are nonconducting and thin and have uniform surface charge densities on their outer surfaces. Figure (b) gives the radial component E of the electric field versus radial distance r from...
43. ### Find the final velocity of the block

Homework Statement So here is the problem, There is a .03kg block that is in an inverted cone, the cone has a slant length of 15 cm and a radius of 4 cm, and the coefficient of friction is .35. The block rotates around the inside of the cone, seamlessly, until it hits the bottom of the cone...
44. ### Exploring Real & Inverted Images with Bi-Convex Lenses

Homework Statement An object is placed between the optical centre and the focus point of a bi-convex lens. The image obtained is always inverted and real. Is this statement true? Justify your answer using the thin lens equation. Homework Equations The Attempt at a Solution
45. ### Electric Potential Energy Problem

Homework Statement Two Charged Objects (Q1= -9.0nC & Q2= 15nC) are fixed in place on the +x-axis. The first charge is 12 cm to the left from the origin the other is 12 cm to the right from the origin. A proton is moved from the origin to a position on the +y-axis 9.0 cm from the origin. a)...
46. ### WJEC GCSE Physics 2 Higher Tier Q5(c)(ii) Help

Homework Statement Question 5 (c) (ii) from the paper physics 2 higher tier January 2014 by wjec. There is no mark scheme at the moment of the paper and I do not understand the question. The paper is at the bottom of "papers" at...
47. ### Physics 2, Three Infinite Straight Wires

Homework Statement https://www.smartphysics.com/Content/smartPhysics/Media/Images/EM/14/h14_threewires.png Three infinite straight wires are fixed in place and aligned parallel to the z-axis as shown. The wire at (x,y) = (-10 cm, 0) carries current I1 = 2.9 A in the negative z-direction...
48. ### Physics 2 , two Styrofoam balls on insulated thread

Homework Statement Two small .1 gram stryofoam balls are strung like beads on a vertical insulating thread. The lower ball is glued to the thread but the upper ball is free to move. Imagine that both are given an equal amount of negative charge such that the upper ball is suspended about the...
49. ### A problem based on Quantum Physics 2

Homework Statement The wave function of a particle in a stationary state with an energy Eo at time t=0 is Ïˆ(x).after how much minimum time the wave function will be Ïˆ(x) again. Homework Equations The Attempt at a Solution Ïˆ(x, t)=Ï†(x)e^(-iEot/h).intuitively i think the answer...
50. ### Physics 2: Electromagnetic Theory (Amperè's Law, Biot-Savart, etc)

Homework Statement First off: these are not homework problems technically, I'm doing these for my own benefit...they're not being graded or collected. Just trying to study for my final. Problem 1 A thin spherical, conducting metal shell has a radius of 15.0cm. A positive charge of 1.30µC...